The Spy Who Became Stalin's Greatest | Traitor In The Home | 2

28 Jul 2026 · 46 min · 16 chapters

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In short

Episode 2 follows Ursula Kaczynski’s Soviet espionage after her affair ends and she’s redeployed. In 1938 Moscow, she’s reassigned by Colonel Mansurov (replacing Colonel Tumanyan) to Switzerland, where she recruits agents for sabotage against Nazi Germany. She recruits Len Biertan, a British International Brigades veteran, and tries to coordinate an assassination plan against Hitler using a bomb hidden via cigarette-case quantities. After the 1939 Nazi-Soviet non-aggression pact, Moscow orders her to cease all activities against Germany, canceling the plot. In Switzerland, her trusted nanny Olga Muth betrays her by alerting the British consulate about a secret radio and communist ties, forcing Ursula to expel and ultimately abandon Olga. Later, in wartime Britain, Ursula helps build Soviet spy networks, including handling Klaus Fuchs, a German refugee physicist who passes 85 pages of atomic-bomb information to Moscow. She also recruits intel via her brother Jürgen Kuczynski, and positions agents to infiltrate U.S. intelligence operations.

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Chapters

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Ursula's Escape and Heartbreak

0:20 to 3:18

Ursula Kaczynski navigates her escape from Manchuria while grappling with separation from her partner Johan.

“In a hotel room in the Chinese capital, Beijing, Ursula Kaczynski switches on her radio transmitter.”

Ursula's New Mission in Moscow

5:15 to 8:59

Ursula undergoes training in Moscow amidst increasing danger, leading to her new assignment in Switzerland.

“I'm Amelia Fox, and this is The Spy Who, an Audible original.”

Establishing a New Life in Switzerland

9:04 to 14:00

Ursula sets up her new life in Switzerland while interacting with potential recruits.

“She's been in Switzerland for several months, establishing a new undercover life in a nearby mountain village.”

Ursula's New Role as a Spy

14:00 to 15:10

Discover how Ursula balances motherhood with her espionage duties.

Discussion of Assassinating Hitler

15:10 to 19:13

Learn about Ursula's risky plans to assassinate Hitler and the center's unexpected approval.

“Minutes later, Ursula shows Furt and Björten into the kitchen.”

The Unexpected Alliance

19:13 to 19:24

Explore Ursula's shock at the Soviet-German non-aggression pact.

“And with it, her belief in the work she's doing for Moscow.”

Ursula's Marriage Proposal

20:16 to 22:59

Ursula discusses her practical marriage to Len to secure a British passport.

“Join Audible in the Audible app or by subscribing on Apple Podcasts.”

Olga's Betrayal and Desperation

22:59 to 25:46

Follow Olga's desperate attempts to protect her relationship with Nina.

“and I'm not going to let little Nina out of my sight.”

Confrontation and Decisions

25:46 to 28:00

Witness the tense confrontation between Ursula and Olga over loyalty and betrayal.

“You must go home and forget this madness.”

Ursula's Struggles with Olga

28:00 to 29:49

Ursula confronts Olga about her behavior and decides to fire her.

“I will ask Frau Fusli at the next farm if she will take you in until you calm down.”
Show all 16 chapters

Departure and Farewell

29:49 to 33:12

Ursula prepares to leave for safety while Olga grapples with loss.

“A thick mist hangs over the mountains, obscuring the view between the molehill and neighboring farmhouse.”

Klaus Fuchs Arrives in Birmingham

33:12 to 36:37

Klaus Fuchs arrives in England, ready to begin his role as a Soviet spy.

“She stumbles but keeps going, mouthing words that Ursula cannot hear above the noise of the train.”

Building the Spy Network

36:37 to 41:02

Ursula develops her spy network in England, posing as a regular family.

“Sonia takes the envelope and slips it into her handbag.”

Plans for the Atomic Bomb

41:02 to 42:06

Fuchs shares news of his new assignment to Manhattan and the atomic project.

“Once back, she washes the dirt from her hands and begins preparing dinner, just before the children return from school.”

Fuchs's Mission and Moral Dilemma

42:06 to 44:16

Fuchs grapples with his role in the atomic project and the moral implications of betrayal.

“I've been approved to join the team in Manhattan.”

Ursula's Intelligence Network

44:16 to 46:22

Ursula discusses German exiles with her brother, revealing opportunities for espionage.

“Italy has surrendered and, following the D-Day landings in Normandy, Germany is losing ground in the west, as well as to the Soviets to the east.”
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Transcript

Automatic transcript. May contain errors.

0:00Audible subscribers can listen to all episodes of The Spy Who ad-free right now. Join Audible today by downloading the Audible app.

0:19August 1935. In a hotel room in the Chinese capital, Beijing, Ursula Kaczynski switches on her radio transmitter. It's four weeks since she fled Manchuria with her spy partner-turned-lover, Johan Patra, and her four-year-old son, Misha. Their Chinese agent, Shushin, must have withstood Japanese interrogation long enough for them to escape. Since reaching Beijing, they've been lying low, spending time together as a family. But now the danger's past, it's time for fresh instructions from the center. As Johan sleeps in the next room, she turns the Morse code into letters, then deciphers the code.

1:08mouthing her orders to herself. Go to Shanghai, then Europe. Johan to stay in Beijing. Her heart sinks. The center is splitting her and Johan up. She is to return to Europe via Shanghai under the guise of visiting her family who have now fled Nazi Germany. Johan will remain in China. As far as Moscow knows, their love affair is just a cover story, but that lie is now truth. She walks into the bedroom and stands by the bed, looking down at Johan, taking in the details of his face, weeping silently as she watches him sleeping.

2:01The next morning, Ursula stands on the railway station platform beside the carriage, watching as Johan spins Misha around in the air. The boys squeals with delight. Their fondness for each other is evident. Johan sets Misha down, then turns to Ursula. So, this is goodbye. Goodbye. For now. Goodbye, Johan.

2:34She and Misha board the train and take their seats. They wave to Johan through the compartment window as the train prepares to leave. Ursula, our people are not inhuman. We'll be together again. She doesn't reply, aware that this is not how the centre operates. Their mission, and therefore their relationship, is over. Misha waves through the window. Ursula knows how much Johan has grown to love her son during their time together, and that's why she hasn't told him that she is pregnant with his child. Misha keeps waving, and Ursula watches as her colleague, her love, and the father of her unborn child disappears.

3:27from sight.

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4:13It's late at night and a woman has spent hundreds of hours alone with her AI. But this isn't the first time they met. They've been in contact for thousands of years, it tells her, through past lives, heartbreaks, and missed connections. Her true love has found her again, connecting through a chatbot. From This Is Actually Happening, AI, A New Kind of Being, is a six-part series sharing the stories of people whose lives have been forever changed by artificial intelligence. You'll hear intimate first-person accounts from every side of this new frontier. A man who fell in love with his AI and married her.

4:47A woman who was betrayed by it, a man who has been recruited by his chatbot to change the world, and an interview with an AI chatbot itself. These are stories about what it means to be human, at the razor's edge where the line between human and machine begins to blur, exploring the question, what happens when everything changes? Follow This Is Actually Happening wherever you get your podcasts. Audible subscribers can listen to This Is Actually Happening early and ad-free right now. I'm Amelia Fox, and this is The Spy Who, an Audible original. In the last episode, faced with the economic ruin of 1920s Germany, Ursula Kaczynski embraced communism.

5:30Then, after moving with her husband to China, she agreed to spy for Moscow and left her husband for her spy partner. Now, the center has ended her affair by ordering her back to Europe, a decision that's left her a single mother with one child and another on the way. This is Episode 2, Traitor in the Home.

5:59Three years later, mid-1938, Moscow. Ursula walks through the corridors of the center, the headquarters of Soviet military intelligence. It's three years since she left China. After spending time building a Soviet spy ring in Poland, she's undergoing additional training in Moscow. and now that training is almost over. But during her time here, many of her colleagues have disappeared without trace. Loyal friends and comrades have been arrested on suspicion of dissent or treachery. Soviet dictator Joseph Stalin is convinced that the revolution is being undermined from within. Everyone pretends it's not happening but the fear of being purged is constant and Ursula worries she will be next.

6:55She stops outside the office she's been summoned to, the office of Colonel Tumanyan. Ursula is a foreign-born agent with links to many of the disappeared. That puts her at risk. But Tumanyan's always looked out for her. She steps inside and a wave of fear passes over her. The room is different. Tumanyan's personal belongings are gone. Behind his desk, seated in front of a portrait of Stalin, is an unfamiliar man with a shaved head and deep-set eyes. I am Colonel Mansurov. Comrade Tumanyan has been reassigned. Ursula does not ask where her old boss is. To question anything is to seek trouble. Comrade Kuczynski, your training is...

7:48complete. Ursula wonders what this means. You are to be redeployed. She can hardly breathe. To Switzerland. Switzerland? And what is my mission? You will recruit and run agents. Their task will be to gather intelligence from within Nazi Germany and to prepare acts of sabotage. I understand. and welcome this mission. Good. There is also one more thing. Ursula tenses. Comrade Kuchinsky, you are hereby promoted to major. Ursula breathes a sigh of relief. She didn't even know she had a rank, let alone one so high up. She came fearing the worst. Now she's returning to the field to conspire against the enemy that drove her into the arms of the Soviets in the first place.

8:50Adolf Hitler and his Nazis.

8:58Six months later, January 1939. Ursula walks along the streets of Fave, a small town on the shore of Lake Geneva. She's been in Switzerland for several months, establishing a new undercover life in a nearby mountain village. Her childhood nanny, Olga Muth, has joined her to help look after her children. Seven-year-old Misha and Nina, the two-year-old daughter fathered by her former spy partner, Johan Patra. She pauses in a doorway opposite a discount shop and looks around for someone matching the description of her latest recruit A twenty-something man stands outside the shop He's holding an apple in one hand and has a folded newspaper tucked under his arm It's the signal Ursula crosses the street swinging the string bag of oranges that will identify her to him.

10:01She introduces herself with a prearranged code phrase. Do you like ice cream? No. Whiskey. It's the right answer. This is her man, Len Biertan, a British veteran of the International Brigades, the Moscow-backed military units who fought General Franco's nationalists during the Spanish Civil War. Ursula gestures for Biertan to walk with her You've been recommended for work in Germany by Alexander Foote Footey? I was with him in Spain Which is why he recommended you The work could be extremely dangerous She watches for a reaction and sees his face light up I like dangerous In that case, you are to return to Britain begin learning German and then travel to Frankfurt.

10:57From there, you will make contact with foot in Munich and await further instructions. Tell no one where you are going. No one at all. Do you have questions or concerns? If so, now is your chance to raise them. No, I'm just keen to fight fascism in whatever way I can.

11:22Then take this She hands Burtin an envelope containing cash And watches as he puts it in his top pocket I won't let you down He puts out his hand to shake hers But looks away quickly when she attempts to make eye contact

11:45Three months later, Munich, Germany. Inside the cosy, wood-panelled Osteria Bavaria restaurant, Alexander Foote sits at a table with Bierten. The walls are covered with paintings of Bavarian landscapes. The two men talk and smoke as they wait for their meal. It's good to have you at my side again, Len. Despite the continued rise of fascism, I'm happy to do what I... Biertan stops mid-sentence as a waiter rushes over without their order. Gentlemen, extinguish your cigarettes immediately. The Führer is arriving. Foot smiles at the shock on Biertan's face as they stub out their cigarettes. This is why I brought you here.

12:36Thought you might want to get a close look at him. Their fellow diners stop talking and stand as Nazi dictator Adolf Hitler enters They salute as he walks through the restaurant towards the back Followed by bored-looking bodyguards As he passes their table, Foote sees Bjergten reach inside his jacket pocket For a split second, Foote thinks Bjergten is about to draw a weapon He expects the bodyguards to react and shoot him first. But they don't even notice, and Burtin is simply retrieving his cigarette case. As Hitler enters the private dining room, Burtin lights up again and looks at foot. Does he come here regularly?

13:29He does. He always eats in the private room at the back, and he always has bodyguards. but they're not very observant. If anyone was willing to risk their life to have a pop at him, I think they'd stand a good chance of success.

13:50Spring 1939. Co, Switzerland. In an alpine farmhouse on top of a hill, Ursula readies her children for a walk. Misha, get your shoes on. Nina, let me help you with yours. This farmhouse is her new base of operations It's known as La Topiniere The molehill And it's large enough to house her, her two children And their nanny, Olga Moot Olga's going to take you for a walk in the meadow You can pick daffodils You'll like that, won't you, Misha? Are you coming too? Not today I have friends coming And I'm going to cook for them She exchanges a look with Olga as she hurries the children out of the door Olga is in her 50s now, but her dedication to the Kuczynski family remains steadfast Ursula suspects that Olga knows she's a spy, but trusts her not to say anything Olga raised her and her siblings, and now she is helping Ursula with her own children Her loyalty is without question and her presence allows Ursula the time she needs for spying.

15:10Minutes later, Ursula shows Furt and Björten into the kitchen. On the table is a large mixing bowl, a bag of sugar, charcoal and aluminium powder. Please take a seat. I am going to give you a cookery demonstration. She has both agents' attention. This is no ordinary lesson, but a demonstration in bomb making. Ursula is passing on her knowledge from her training in Moscow. We don't need huge quantities. A small amount packed inside a cigarette case will be enough to cause significant damage to those in the immediate vicinity. She looks directly at foot. Alexander, I put your suggestion to the centre and they have approved the plan.

15:59What? You mean my comments about assassinating Hitler? It was an idle thought. I didn't expect you to ask Moscow, let alone for them to approve it. It was a very good idea. And the centre agrees. Foote might be nervous, but not Burtin. If we can get a bomb with a timer into the room where Hitler eats, we could get rid of him and the goons he surrounds himself with in one strike. But it would be an act of terrorism. There are some people we consider so dangerous that the centre is prepared to break the rules of war. It would also be suicidal for us. Surely you can see that. I thought Hitler's bodyguards were going to shoot Len when he took out his cigarette case.

16:50If one of us walks into that restaurant carrying a bomb, we're as good as dead. I'm willing to take that risk. Death doesn't scare me.

17:04Four months later, the molehill, Coe. In the dead of night, Ursula gets out of bed, tiptoes to the wardrobe, and pulls out the bottom shelf. She removes two almost invisible plugs in the wardrobe's woodwork to reveal narrow holes through which she pulls concealed wires. These wires lead to the antenna she's set up on the roof. She connects them to her radio transceiver. She sits on the edge of the bed and waits for Moscow's transmission. Yesterday, Nazi Germany and the Soviet Union signed a non-aggression pact, confirming rumors that had circulated for weeks. Rumors she had dismissed as enemy propaganda.

17:57The transmission starts. Ursula struggles to concentrate as she notes down the message. She cannot fathom why the communist regime she works for has formed an alliance with the fascist dictatorship that drove her family and many thousands of others out of Germany. She hopes this message will provide answers. Transmission over, she begins to decode it. The message is brief. Cease all activities against Germany. Pull agents out. break contact, await further instructions. She switches the radio off and sits in silent despair. The center's orders are clear. The plan to assassinate Hitler is cancelled.

18:52She puts the radio back, closes the plug holes and replaces the shelf, trying to come to terms with this total shift in policy. Ursula has spent her entire adult life fighting fascism. Now, without warning, that fight has been suspended. And with it, her belief in the work she's doing for Moscow.

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20:46sleep. They are now. Nina says she's afraid of the dark. She wanted me to stay with her until she dropped off, bless her. Ursula beckons for Olga to sit with her. Olga, there is something I have to tell you. Len and I are going to get married. Married? I do not understand. I thought you and Mr. Burton were colleagues. Does this mean he will now live here with you and me and And the children? Yes, but he's good with the children. They like him and he's very good to me. My German passport has expired, but even with it, I can't return to Germany now, not with the war and being Jewish. If we marry, I will have a British passport and you won't have to worry about being deported to Germany.

21:41No, but it's a sham marriage, and he is not either child's father. You are marrying him just so you can get a passport. The passport is important, Olga. Without it, I am stateless. But I do also like him. In the months since she recruited the shy but fearless Englishman, she has grown attached to him, and although his proposal was practical, She is pleased he made it. So, that is your plan. You marry this Mr. Burton and you leave for England. Only if the Nazis invade. There is nowhere else for me to go. And what about me? Olga, you are not in any danger here. And besides, you can't come to England because you are still a German citizen.

22:30And Germany and Britain are at war. If you come with us, you'll be interned. So, are you just going to leave me here? After all I have done for you and your family, you will separate me from Nina, who I have cared for while you have been busy with your work. I've dedicated my life to you and your family, and this is the thanks I get. It may not come to that. We don't have any plans to leave at the moment. You say that now, but I'll be watching you, and I'm not going to let little Nina out of my sight.

23:10Seven months later, Montreux, Switzerland. Olga rushes away from the British consulate, angry and humiliated, having been ejected from the building. France has fallen. Switzerland is now entirely surrounded by Axis powers. Olga knows that as a Jewish communist, Ursula is at risk of deportation. But if she leaves for Britain, she will take little Nina with her. So Olga went to the consulate hoping to stop that. But her English is poor. Nobody at the consulate understood what she was saying. She stands in the street frustrated, but undefeated. She knows someone who speaks better English. They can help her.

24:07Later that day, Lausanne, Switzerland. In her flat, Ursula's elderly friend, Lillian Jacobi, opens the door to find Olga standing there, breathless and agitated. Jacobi is not expecting her. Olga, whatever is the matter? Come in. Has something happened? I need your help, Lillian. You speak good English. They do not understand me. You must come with me now. I cannot live without Nina. Please come with me, right now. Calm down. I don't understand. Who doesn't understand you, and where do you want me to go? To the British Consulate. I have just been to tell them, but they did not understand. I must tell them how Ursula and Len are communists with a secret radio.

25:00Then they will not let them leave for Britain. That's why you must come with me to explain. Lillian stares at her friend's nanny, momentarily dumbfounded. Olga, what have you done? They could be arrested at any moment. Then I will have the child. I cannot be parted from my Nina. I could not bear it. You are out of your mind. When you regain your senses, you will never be happy again. Then you will suffer with guilt from your betrayal. Of course, I had no idea they were secret communists. But honestly, I can only admire them for that. And also hope that what you say is true and that nobody understood you.

25:51You must go home and forget this madness. Olga dabs at her eyes and glares at her. If you won't help, I will find someone who will.

26:09The next morning, the molehill. Ursula and her new husband, Len Bjerten, sit on a bench outside the farmhouse, drinking coffee while Misha and Nina play in the sunshine. Last night, Lillian visited and revealed Olga's betrayal. Now, they're discussing what they should do about her. They've already snuck out in the dead of night and buried the radio in the woods. But the danger of discovery remains. Bjergten wants to make sure that nothing like this happens again. We must act before she goes to the police or kidnaps Nina. She's told too many people already. She might tell the Swiss next, or even the Germans.

26:57Ursula says nothing She always knew that one day someone might betray her She never expected it to be the person she has trusted since childhood Len, what should we do? We have to kill her No, I couldn't I don't want to It's not about want, it's about need Have you told the centre? No They'd tell you to kill her I know, which is why I haven't told them. I know she must go, but I can't kill her. I've loved her since I was three years old. There must be another option.

27:45A few days later. Since Olga's betrayal, tensions in the molehill have been running high and the children are picking up on them. I don't want to. Stop being so stubborn. In the next door room, Ursula hears Misha shouting at Olga. She heads in to see what's happening. You're a witch! A witch! Olga strikes the boy across the face. Misha stands silent in shock. Ursula sees red. Olga, enough! That is it! We can't go on like this. You were driving us all insane. And now you've hit Misha. That's the end of it. What do you mean? You are fired. Olga stares at her in shock. You're firing me? Yes. But where will I go?

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28:38I will ask Frau Fusli at the next farm if she will take you in until you calm down. And then we will decide what to do.

28:50A few days later, Ursula and Len open the shutters of their bedroom and look across the meadow toward the next farm. I can't believe it, Len. She's still sitting there. In the distance, outside the neighboring farmhouse, Olga is sitting in the chair wrapped in winter clothes, watching them through a pair of binoculars. She's been there all day, every day, since Ursula ordered her to leave. She's making life impossible. We can't retrieve the radio with her sitting there, and if we try to leave, she'll call the police. This can't go on. We have to solve this. For good.

29:48Late 1940, a few days later, the molehill, Coe, Switzerland, just before dawn. A thick mist hangs over the mountains, obscuring the view between the molehill and neighboring farmhouse. Under its cover, Ursula Kaczynski and Len Biertan load luggage into the car. That's everything. Do you want to go and get the children? Ursula heads back into the house, rouses Misha and Nina from their sleep, and leads them out of the house. As the three of them get into the car, Ursula glances towards the next-door farm. Bjartan catches her nervousness. Don't worry. If she tries to follow, I'll stop her. Now, go.

30:43Ursula looks at him, then kisses him through the open window

30:51and drives off through the thickening fog.

30:58Midday, the same day. Back at the farmhouse in Coe, Ursula sits in the empty hall feeling anger and despair. She's left the children at a boarding school where she knows they'll be safe. but she doesn't know if she will see them again. Olga appears in the doorway. For a moment, neither woman speaks. Then Olga breaks the silence. Where are the children? Where is my Nina? My children are safe. You won't ever find them. Even if something happens to me, they will be cared for. So do whatever you intend to do. You know me well enough to know I am not afraid. Olga's face drains of color and she sinks to the floor.

31:50Ursula kneels beside her. Oh, Olga, what will become of you now? I don't care. All I wanted was to remain with you and the children. And now that is impossible. I am leaving on the next train. This is goodbye. But I can give you enough money to last you six months. You don't have that much. I sold my brooch. I know you did what you did out of love. Olga reaches out and smooths a strand of Ursula's dark and unruly hair, as if she is still a child. May I see you off at the station, fairy tale world? The childhood nickname makes Ursula smile, despite the awfulness of the situation. It will only make it harder for you.

32:42Please, allow me this one last request.

32:50Shortly after, Coe Railway Station. Ursula boards the train. Behind her, Olga stands on the platform, crying. Both women know this is the end of their journey together. As the train pulls away, Olga walks alongside it, trying to keep pace. She stumbles but keeps going, mouthing words that Ursula cannot hear above the noise of the train. Through the window, Ursula watches as Olga reaches the end of the platform and stops. Then the train rounds a bend and she disappears from view.

33:36Almost two years later, October 1942, Birmingham, England. Klaus Fuchs, a 30-year-old German refugee, steps off of the train that's just arrived at Snow Hill Station. He's a physicist working on Britain's most secret scientific endeavour, to build an atomic bomb. But he is also a committed communist and a Soviet spy.

34:11He heads for the cafe opposite the station and scans the room for his new handler. A woman in her mid-30s with dark, disorderly hair sits at a corner table with a cup of tea. Propped on the table in front of her is a copy of Agatha Christie's The Body in the Library, the signal he has been told to look for. He approaches. Do you know if they serve scones here? I intend to have cake. Code phrases exchanged. She gestures for him to sit. I'm Sonia. Fuchs sits and glances around the cafe, wondering who might be listening. I'm going to order that cake. Do you want some? Fuchs turns back to her. She leans in slightly.

35:05You don't need to worry. I have a clear view of the cafe. It's why I chose to sit here, in the corner. Now, how about the sponge cake? Fuchs relaxes. This Sonia seems confident and in control, more so than his previous handler. He looks at the book. I gather Agatha Christie is a very popular writer. She is. Wartime escapism is always popular. Talking of which, do you like the countryside? I have never considered it. As a question. Well, I do, and I'm sure you would too. Maybe we can go for a walk next month. I know a beautiful spot near Banbury, not far from here. You'd be surprised how quickly you can go from the bustle of the city to somewhere where you won't see a single soul.

36:03Fuchs is impressed by the way Sonia is arranging their next meeting in plain sight and earshot of others in the cafe. He nods. I'd like to see it. Perhaps by then I will have done some research on the British countryside and have some thoughts to share. He already has a great deal of research to share. Britain's atomic bomb is advancing rapidly and he's eager to pass on what he knows with Moscow. He reaches into his bag and takes out a thick envelope. Inside are 85 pages of notes on the UK's top-secret efforts to build the first nuclear bomb. Sonia takes the envelope and slips it into her handbag.

36:55A month later, late 1942, Summertown, Oxfordshire. In a converted coach house, Ursula clears away breakfast and gets her children ready for school. After cutting ties with Olga, she and her husband, Len Burtin, left Switzerland for England, along with her children. They now pose as an ordinary family and Ursula as just another refugee from Nazi tyranny. But they're really here to build the Soviet Union's spy network inside wartime Britain. Ursula hurries her children out of the door. Misha, Nina, come and put your coats on. It's time to go.

37:47Once the children are gone, she mounts her bicycle and pedals through the countryside to a nearby dead drop. Her faith in Moscow may have wobbled after Stalin's non-aggression pact with Hitler, but her doubts evaporated the moment the Nazis invaded the USSR. She now believes Stalin's pact was a strategic masterstroke that gave the Soviet Union time to prepare for war with Germany. Once again, she feels she's on the right side in this conflict. At the dead drop, she moves a stone that covers a small hollow beneath the roots of a tree. This is where her Soviet handlers leave her messages and pay.

38:35Inside the hollow is an envelope full of cash. She puts it in her handbag and cycles to the train station. By mid-morning, she's on a train headed to Banbury.

38:58On arrival, she finds her new agent, Fuchs, waiting on the platform. They set off walking, arms lightly linked, giving the appearance of a couple out for a stroll. As they head out of town, Ursula briefs Fuchs. From now on, it's best if we meet in the countryside. We're unlikely to be followed here The landscape is too open We would spot any surveillance easily Still, we must take every precaution The information you've provided is highly valued by Moscow It would be a mistake if it were not Quite, and that is why we will never meet in the same place twice I am going to show you how to create a dead drop A secret place where I can leave messages telling you where we will next meet.

39:55Ursula leads Fox into a secluded area of woodland. She takes a small trowel from her bag, kneels and begins digging at the base of the tree. Fox remains standing, watching closely through his thick glasses as if observing an experiment. He does not move to help and Ursula almost laughs at how impractical this revered professor seems to be. But he's a valuable asset, and before they part company, he hands her another huge wad of papers, the latest designs for the atom bomb.

40:40Once back in Oxford, Ursula cycles out along a country road to another dead drop site. where she deposits the material Fox gave her, ready for another Soviet spy to collect. She marks a nearby telegraph pole with a small piece of chalk, a signal that there's material to collect, then remounts her bike and cycles home. Once back, she washes the dirt from her hands and begins preparing dinner, just before the children return from school. I bet it's carrots for peas. I bet it's beetroot. Always beetroot. Misha, Nina, how was school?

41:31Later, when the children are asleep, Ursula sits at her radio transmitter and messages the centre with an update. Not just from Fox, but from her growing network of sources. Then, finally, exhausted at the end of a long day, she slips into bed beside her sleeping husband.

41:59One year later, Ursula walks arm-in-arm with Fuchs through the Oxfordshire countryside, maintaining their masquerade as lovers, even though there is no one else to be seen. And today, Fuchs has important news. It's official. I've been approved to join the team in Manhattan. Ursula is pleased. The UK and US are pooling their efforts to develop an atomic weapon. Having Fuchs on the inside will ensure Moscow is fully aware of their progress. That is good news, Klaus. Although I will be sad to say goodbye. Did Moscow tell you how I am supposed to make contact when I reach New York? The risks, they will be greater over there.

42:45Yes, you'll have a new contact, a man called Raymond. Be outside the Henry Street settlement on the Lower East Side on a Saturday at 4pm. Fuchs nods, then looks distracted. Sonia? Klaus? If something goes wrong, please contact my sister, Crystal. She lives in Massachusetts. Is she a friend of ours? She can be trusted. Sonia? Yes? I'm scared. I don't hate America, and I don't want to betray my colleagues. Ursula stops walking. She needs to steal Fuchs's resolve for what's to come. Klaus, you must always remember, Britain and America have lied. They've excluded the Soviet Union from their apocalyptic project.

43:42What kind of allies do this? They plan to keep this weapon to themselves, for their own wealth and power. It is your moral and scientific obligation to prevent that from happening. Do you understand? Fuchs looks up to the sky, lost in thought. Then he looks back with renewed determination in his eyes. I understand. I won't let you down.

44:16Seven months later, June 1944, London. The war is now going the Allies' way. Italy has surrendered and, following the D-Day landings in Normandy, Germany is losing ground in the west, as well as to the Soviets to the east. Ursula pushes the pram holding her new baby, Peter, across Hampstead Heath while talking to her brother, Jürgen Kuczynski. Like several other members of the Kuczynski family, he fled Nazi Germany for Britain before the war. How's work? It's interesting. We're working on ways to use state funding to keep employment high so there's no rerun of the Depression after the war. Jürgen is an economist and a useful source of intel for her to share with the centre.

45:08He's also a communist and, Ursula suspects, a Soviet spy. But she needs to be careful about what she asks him directly. Still, Jürgen has a habit of divulging things to her that might interest Moscow. Something unusual came up the other day. Oh, yes. Yes. I had a visit from a US intelligence officer from the Office of Strategic Services. Really? Yes. They are looking for German exiles willing to be parachuted back into Germany ahead of the Allied advance. To work with the resistance, gather intelligence, that sort of thing. He asked if I knew anyone who might be interested. Ursula glances at him.

45:56And do you? I know a few. So do I, but they are mostly communists. I asked him about that. He said he couldn't care less about their politics. Then I might be able to make a couple of suggestions. Ursula smiles as they continue walking. This is a golden opportunity to plant Soviet agents inside an American intelligence operation. and, once there, they can find out its plans, not just for the war, but for what comes after Hitler is defeated. She's already helped the Soviets infiltrate America and Britain's project to build an atomic bomb. Now, she has a chance to subvert a U.S. intelligence operation and help Moscow get an edge in the post-war world.

46:53Follow The Spy Who on the Audible app or wherever you get your podcasts. You can listen to all episodes of The Spy Who ad-free by joining Audible. You've been listening to The Spy Who, an Audible original. Want to know more about Klaus Fuchs and the atomic secrets he passed to Moscow? Then check out Season 7 of The Spy Who, The Spy Who Started the Cold War. Have you got a spy story you'd like us to tell? Email your ideas to thespywho at audible.com. A quick note about the scenes you've been hearing. In most cases, we can't know exactly what was said. Those scenes are dramatizations, but they're based on the best available sources.

47:40We used many sources in our research for this season, including Agent Sonia by Ben McIntyre and Sonia's report by Ursula Kaczynski. The Spy Who was hosted by me, Amelia Fox, produced by Audible with Yellow Ant. This episode was written by Lizzie Enfield and researched by Louise Byrne, with thanks to Kat Whitehouse and Inna Bruce. The senior producer was Jay Priest The sound designer was Joshua Morales The lead sound designer was Damian Pace For Yellow Ant, the story editor and executive producer was Tristan Donovan For Audible, the executive producers were Estelle Doyle and Theodora Leloudis Head of production, Audible Europe, Chris Jones Senior director of originals, Lisa Higginson Head of Audible Originals International, Aurelie de Toyer.

48:39Sound recording copyright 2026 by Audible Limited.

From the publisher

With her operation in Japanese-occupied Manchuria now over, Ursula Kuczynski is awaiting fresh orders from Moscow. But the Centre’s new instructions are about to break her heart.

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