In Moscow, young Arkady hits his older brother, Jora, with snowballs during their regular winter games. Annoyed by Arkady’s gloating, Jora retaliates with a snowball packed with mud and stones. He regrets this immediately and shouts a warning, but Arkady turns directly into it, and the impact knocks out one of his teeth. Humiliated and bleeding, Arkady frantically searches for the lost tooth in the snow. Jora rushes over, filled with regret, but Arkady shakes him off and runs away.

MGB officer Leo Stepanovich Demidov arrives at an apartment block to address a delicate situation. Four-year-old Arkady Andreev was found dead on railway tracks three nights earlier. The death was officially ruled an accident, but the boy’s father, Fyodor Andreev—a low-ranking MGB officer and Leo’s subordinate—insists that his son was murdered and has been spreading this claim among neighbors. In Leo’s eyes, calling this death a murder is not merely factually wrong but politically dangerous because it contradicts state doctrine that serious crime does not exist in Soviet society. Leo’s task is to restore the family’s faith and end the speculation.

At the crowded apartment, Leo presents the official report, but Fyodor and his elderly mother challenge it, claiming that a witness said the boy was found naked on the tracks with dirt in his mouth. A second witness, Galina Shaporina, previously stated that she saw Arkady in the company of a man. Now, however, she is summoned and nervously states that she saw only a man working on the tracks; she then quickly leaves. Leo instructs Fyodor that the murder talk must end, and Fyodor reluctantly agrees. As Leo departs, Arkady’s older brother, Jora, confesses that he threw a stone-packed snowball at Arkady before he died; he says that this is why Arkady had dirt in his mouth and worries that he stumbled onto the tracks because the blow disoriented him. Leo reassures Jora that Arkady’s death was not his fault and advises him not to burden his parents with the information.

Exhausted after three days without sleep, Anatoly Brodsky breaks into a barn in the village of Kimov and collapses on straw. The barn’s owner, Mikhail Zinoviev, arrives and raises a pitchfork to stab Brodsky. However, he abruptly drops the weapon and begs for forgiveness as Brodsky wakes. It emerges that Brodsky is fleeing the MGB. Earlier that evening, he had arrived at the home of Mikhail, an old friend, but Mikhail and his wife refused to shelter him, fearing execution. Brodsky bargained, offering to stay only one night and break into the barn to make it appear he was an uninvited intruder. Now, Brodsky forgives Mikhail for having second thoughts and nearly killing him: “You’re not to blame. I might have done the same. […] I’m still your friend and I’ll always be your friend” (36). Mikhail then returns to his house. His wife stares from the window, disappointed that he did not kill Anatoly to protect their family.

Leo searches the apartment of Brodsky, whose work as a veterinarian brings him into frequent contact with foreigners seeking treatment for their pets. Brodsky is suspected of being a spy but has escaped, and all documents have been burned. Leo realizes that he made a critical error by ordering surveillance rather than arresting Brodsky immediately, giving him time to detect the watch and flee. After intimidating a neighbor into revealing that Brodsky corresponded with a friend in Kimov, Leo identifies the friend as Mikhail Zinoviev, whom Brodsky treated during World War II, when he worked as a field doctor (the reason for Leo’s “sentimentality” in deciding not to simply arrest Brodsky—he also served in the war).

Leo’s deputy, Vasili Nikitin, has just searched Brodsky’s veterinary clinic and gives Leo a letter implying that Brodsky has sought refuge in Kiev. Vasili wants to pursue this lead, but Leo is certain that the letter is a forgery and overrules him. He orders the team to Kimov, knowing that his career depends on recapturing Brodsky alive.

Leo’s team struggles through a blizzard in a military truck heading to Kimov. Leo senses growing hostility from his men, partly due to Vasili’s efforts to undermine him. When the truck becomes stuck in snow, Leo realizes that the driver—chosen by Vasili—is deliberately sabotaging the mission. He takes over the wheel himself.

At Mikhail’s farmhouse, Leo takes amphetamines, as he routinely does during high-stakes missions: “Now prescribed to him by the MGB doctors, he’d used [the drug] repeatedly since the war, whenever a mission needed to run all night. Its usefulness couldn’t be underestimated” (52). He finds the family at breakfast and demands to know Brodsky’s location. Fresh tracks in the snow lead from the barn toward the fields. Leo strips off his coat and pursues Brodsky on foot, ordering three agents to follow. The agents move slowly, reluctant to exert themselves for a commander whose authority is slipping. Leo runs ahead alone.

Brodsky, realizing that escape is impossible, deliberately breaks through river ice to drown himself. Leo jumps in, drags him out, and performs life-saving measures on the bank.

Back at the farmhouse, Leo finds Mikhail, his wife, and their two daughters kneeling in the snow with hands bound. Before Leo can intervene, Vasili executes Mikhail and his wife. Leo draws his gun and orders Vasili to stand down before he kills the children. Vasili complies, claiming that he was making an example of traitors. Leo strikes him with his gun, orders him to stay behind with the local militia, and returns to Moscow with Brodsky and the two orphaned girls.

At the Lubyanka headquarters of the MGB, Major Kuzmin congratulates Leo on capturing Brodsky but questions his judgment in delaying the arrest. He also reprimands Leo for drawing his gun on a fellow officer, warning that taking justice into his own hands is unacceptable, though he agrees that Vasili disobeyed orders by executing the parents. He then assigns Leo and Vasili to conduct Brodsky’s interrogation together.

In the interrogation cell, Brodsky tells Leo the names of his clients—pet owners, not spies. Doctor Hvostov arrives and administers camphor oil injections, which induce seizures and supposedly prevent lying. The procedure causes violent convulsions that break Brodsky’s wrist. Questioned during the seizure, Brodsky can only repeat the names of his veterinary clients. Leo realizes with certainty that Anatoly Brodsky is innocent—a veterinarian who simply treated a foreign diplomat’s dog.

After Leo leaves the interrogation (and work) claiming illness, a doctor named Zarubin is sent to Leo’s apartment to assess his condition. Zarubin has instructions to treat him if he is telling the truth and drug him if he is not, buying time for the MGB to decide what to do with him: “The major was concerned by the timing of the departure. Was Leo really sick? Or was there another reason for his absence?” (87).

Arriving at the apartment, Zarubin immediately notices the beauty of Leo’s wife, Raisa, who ushers him inside. Zarubin examines Leo, sedates him, and then informs Raisa that while her husband is genuinely ill, Zarubin will only testify to this if she agrees to sleep with him. Raisa wards him off with a kitchen knife and appeals to Leo’s supposed friendship with Major Kuzmin. After Zarubin leaves, however, she realizes that she and Leo are now in great danger.

Meanwhile, Leo has nightmares of people he’s arrested or otherwise harmed; visions of Zinoviev and his daughters interrupt a memory of Leo’s wedding celebrations. The sequence concludes with Leo dreaming of drowning.

When Leo wakes, Raisa is there, and he talks about the moment he first saw her. After he falls back asleep, Raisa reflects on an earlier visit from Kuzmin, who told her that Zarubin had told him that Leo’s illness was genuine. He then handed her a bag of fruit—a gift from Zarubin. Disgusted, Raisa initially threw the fruit away when Kuzmin left but then plucked it from the trash.

After three days at home, Leo returns to work. Kuzmin informs him that Brodsky confessed after two days of interrogation and was executed. The confession names seven people working with foreign agencies. Kuzmin hands Leo surveillance photographs of the seventh suspect—Raisa.

Raisa is a schoolteacher whose subject, political studies, invites intense scrutiny; she is often tasked with teaching propaganda, and students go out of their way to prove their patriotism while avoiding attracting attention to themselves. She has formed a friendship with a language and literature teacher named Ivan Kuzmitch Zhukov, and he sometimes covertly slips her copies of foreign books to read. Today, she leaves work with Ivan.

Meanwhile, Leo observes Raisa from a distance. He reflects on a time he once had Raisa followed, fearful that she was having an affair. Now, he suspects that Vasili inserted Raisa’s name into Brodsky’s confession as revenge. Kuzmin gave Leo the choice of investigating her himself or handing the case to another operative. Leo accepted the assignment.

Leo follows Raisa to Novokuznetskaya station, where she unexpectedly gets off the train with Ivan rather than continuing home. By this point, Leo has realized that another MGB agent is following him—not Raisa—to ensure that he conducts the investigation properly. He must choose whether to expose her by following or stay on the train to protect her. He stays on the train and then loses his tail at the next station.

Leo visits his parents’ apartment and explains the situation: Raisa has been named in a spy’s confession, and if he defends her and is wrong, they will all be sent to the Gulags. His father admits that he cannot advise Leo to sacrifice himself for Raisa, even if it would be the right thing to do. When Raisa arrives for her weekly dinner with his parents, she reveals that she had been late due to a doctor’s appointment—she is pregnant.

Unable to sleep, Leo contemplates memories of people he has arrested and families he has destroyed—things he had always believed would never happen to him. Around dawn, he searches the apartment thoroughly per MGB procedure—ripping up floorboards, checking every book and wall, feeling through the mattress. While he is doing so, Vasili arrives with two agents, including Fyodor Andreev, brought deliberately as an insult. Claiming to assist with the search, Vasili shows Leo surveillance photographs of Raisa and Ivan, who is suspected of treachery, and urges him to denounce her and move on.

Fyodor then speaks privately to Leo, saying that he knows his own son was murdered but was forced to accept the official story. He tells Leo to do the same—denounce Raisa and survive. Leo also learns that Vasili has discovered the surveillance Leo secretly ordered on Raisa three years earlier for suspected infidelity.

After the men leave, Leo begins putting the apartment in order. While replacing Raisa’s clothes, a copper coin falls out. When it hits the floor, it splits in half: It is a hollow coin designed for smuggling microfilm.

At his formal deposition, Leo contemplates whether the coin is a test of loyalty orchestrated by Kuzmin to see whether he will put the state before his personal life. If so, denouncing Raisa would not bring her to harm but would ensure his own safety and that of his parents. On the other hand, all six other names from Brodsky’s confession have already been arrested and confessed, lending credibility to the idea that Raisa is in fact a spy. In either case, defending Raisa will almost certainly put Leo himself in jeopardy.

Kuzmin opens the deposition, states that Leo himself is not suspected of any crimes, and asks what he found in his investigation. Leo stands and declares his wife innocent.