During a routine night-time traffic inspection in East Berlin in June, 1980, police officer Martin Kupfer meets beautician Julia Hausmann. Before he’s finished questioning her, Martin has fallen in love.

Martin lives with his parents, separated from his ex-wife and his seven-year-old daughter, Lisa. Julia is engaged to the German-American Robert Schnyder, who visits her almost daily from his home in West Berlin. Her mother is the famous singer-songwriter Dunja Hausmann, who is critical of the regime and doesn’t approve of her daughter’s relationship. What Martin and Julia do not know is that Dunja was the first love of Martin’s father, Hans Kupfer, who, in his position as a senior officer at the Ministry for State Security (the Stasi secret police), used every means in his power to protect the dissident artist from the clutches of his colleagues. But the night-time traffic stop has brought Dunja’s daughter Julia and her American boyfriend to the Stasi’s attention. Hans has no choice but to have the couple placed under surveillance. Martin’s brother Falk, also a member of the Stasi, throws himself into the case with great enthusiasm. He is angling for a promotion and is hoping to win the necessary support from his father. When he sees his brother Martin looking to make contact with Julia, Falk is shocked. His Stasi superior, Gaucke, threatens to derail Hans’ and Falk’s careers if Hans does not get his youngest son under control. On learning that Julia is Dunja’s daughter, Hans is afraid that he could be her biological father and, 25 years later, reappears in Dunja’s life. She owes him an answer, but uses all her means to prevent her daughter having anything to do with the Kupfers. Julia is torn. After meeting with Martin in the upscale Weissensee neighborhood where he lives with his family, she too has fallen in love. But her boyfriend Robert plans to smuggle her to the West in a hidden compartment in his Mustang. Julia is torn, but it’s too late to back out. And on this night in June, with Julia hidden in the car, Robert Schnyder is pulled over at a police checkpoint…

Robert Schnyder is taken into custody for aiding and abetting illegal emigration from the German Democratic Republic. Falk questions him, intending to use every means possible to squeeze a confession from Robert that will implicate Julia. But Robert denies the young woman wanted to flee with him. Julia is also arrested on her front doorstep as she arrives home later. Falk puts pressure on Julia during her questioning. When Hans intervenes and lets the young woman go, Falk is furious – and to compensate, ramps up the interrogation of Robert Schnyder. Hans, afraid that Martin is endangering the family’s standing, forbids him all contact with Julia. But despite the immense pressure from both families, the love between Julia and Martin grows deeper. Dunja Hausmann has to present the gentlemen at the Ministry for Culture with the set list for her next tour, and receives permission to appear in public. But when she sings forbidden songs in Erfurt, she is arrested, and only after hours of questioning is she sent home. Tired and dejected, she arrives in her apartment and encounters her daughter, who is there with Martin. She abruptly shows the young man the door. Julia leaves with him. The young couple are desperate: where will they stay? Meanwhile, Robert Schnyder has given up resisting after hours of questioning and wishes to make a statement. Flush with victory, Falk makes his way, together with Hans, to the cell – and finds the American unconscious on the floor…

Martin and Julia apply for a joint apartment and get lucky: the woman at the housing office doesn’t give them any trouble. But one call from Hans is enough to have the apartment taken away from them again.

Following his collapse in the cell, Robert Schnyder is admitted to the hospital in a coma. But although the Schnyder case does cause difficulties in foreign relations, Falk receives recognition from Gaucke, his Stasi superior. Against Hans’ will, he is given a free hand in the Hausmann case. Immediately he has Dunja’s apartment bugged. Hans’ protests against the surveillance fall on deaf ears. When the West Berlin music agent Meigold, who has suggested that Dunja release a record in the West, produces an LP with her in her apartment, it is recorded twice at the same time: once by Meigold and once by the Stasi. Falk, who is unable to accept his brother’s love for Julia and fears consequences at work as well as for the family, persuades Martin’s ex-wife Marion to use their daughter Lisa as a means to exert pressure and win Martin back. This leads Marion to withdraw child visitation rights from her ex-husband as long as he is with Julia. Martin is desperate, thinking he has to decide between Lisa and Julia, and knows that in the end he has no choice but to separate from Julia. When Marion goes to pick up her daughter from daycare, the girl has already left for home on her own: she wants to go see her father. Marion raises the alarm. The family panics: a sex offender is active in the area and might have come across the girl. Martin immediately organizes a large-scale search for his daughter.

The search for the missing Lisa is in full swing. Hans and Marion blame Falk: his actions have caused the whole situation. When Martin discovers Lisa eating ice cream with a stranger, the man is arrested and charged with child abduction.

Marion apologizes to Martin for her behavior and asks him for another chance. In reconciliation, she invites him for a meal. Martin tells her he will not be coming back – he’s in love with Julia. The Stasi observes that music producer Meigold is meeting with a smuggler who is charged with illegally bringing the tapes of Dunja’s songs to the West. Meigold is arrested at the handover. When he confesses, Falk feels he has finally achieved his goal: Gaucke gives him permission to arrest Dunja. Hans suggests instead that they recruit Dunja as an informer. Falk therefore makes the singer an offer: if she cooperates in future, she won’t be charged or arrested. Instead of replying, she throws him out the apartment. Dunja and Julia now have a terrible argument, with Dunja accusing her daughter of telling Martin about the plan to smuggle the tapes. Julia, hurt by the accusation, packs her bags to squat in an empty apartment. Hans lures Dunja out of her bugged apartment to speak with her in private, and to persuade her once again to cooperate. She learns her apartment is bugged, and that she has falsely accused Julia. By chance, Hans’ wife Marlene sees her husband with his ex-lover. In her despair she confides in her eldest son: Falk should make Dunja disappear. Falk succeeds in persuading Gaucke and the Minister that the singer should be arrested for the illegal export of the tapes. During the arrest, he permits Dunja to go to the bathroom alone to get dressed – and as Hans comes in, Dunja is lying motionless in the tub…

Dunja’s life hangs by a thread following her suicide attempt. Falk now has to account to his superiors for what happened: to his father, as well as to Gaucke and the Minister’s deputy, Korwitz. Falk is given the chance to find a way to cover up the incident.

Hans, in turn, is promoted to guest lecturer at the Stasi Academy in Potsdam-Eiche. Julia, unaware of all this, learns from a neighbor that Dunja was taken away in an ambulance. She bursts in on the Kupfer family to ask for Martin’s help in finding her mother. Hans confesses that Dunja is in the hospital following a suicide attempt. When Martin realizes his brother and father are involved, he packs his bags and leaves his parents’ house with Julia. As a police officer, he is able to find out which hospital Dunja is in, and Julia succeeds in sneaking into her room. Dunja is in bad shape – she doesn’t recognize her daughter. Hans meets Julia at her mother’s sickbed. There follows an exchange in which he confesses his affair with Dunja to Julia and offers her his friendship, but Julia rejects him. Marlene knows immediately where her husband has been as he returns home. She tells him she knew of his relationship with Dunja from the beginning. The tension between Falk and Martin reaches breaking point as Martin refuses to arrest peaceful concertgoers during a raid on an illegal concert, thus disobeying his brother and his superiors. Blows are exchanged, and for the first time Martin comes out stronger. Falk explodes with fury and threatens to destroy both his brother and his love. Among the arrested concertgoers is Julia’s friend and co-worker, Monika Schrader. Falk interrogates the young woman and recruits her as an informer. Her task is to keep an eye on Julia.

With Dunja recovering, Falk pays her a visit accompanied by a lawyer. He threatens to have her declared incompetent following her suicide attempt if she does not cooperate with the Stasi. Dunja relents and signs the declaration of commitment.

As a reward, Gaucke dangles the prospect of promotion to Hans’ position before Falk’s eyes – as soon as Hans makes a mistake. Until then, he should concentrate on solving the Martin and Julia problem. But Falk has other concerns: his son Roman has failed a gymnastics exam. Falk uses his contacts to pull strings to get the boy into a prestigious sports academy. When Martin learns Julia is expecting a child, he is beside himself with joy. He takes his last possessions from home and tells his dad about the illegal apartment and Julia’s pregnancy. Hans promises to keep the secret. Meanwhile, Dunja returns home. When her artist friends come to visit, she is plagued by guilt at being a Stasi informer. She asks them to leave immediately. A call from the Stasi listening post reminds her of her cooperation. Julia meets with Dunja. Using pen and paper, Dunja communicates her situation to her daughter. Upset, Julia tells her friend Monika about her contact with a West German journalist, and her plans to tell him everything about the Stasi’s blackmailing of her mother. Monika warns her against the idea; it will only hurt Dunja. Then she reports Julia’s plans to Falk. Martin and Julia have a fight: fearing for her safety and that of their child, Martin forbids Julia from meeting with the journalist. But it’s precisely because of their child that Julia wants to change things. Martin runs back to his parents’ house. Hans warns his son against making the same mistake he once did: giving up his true love due to outside circumstances. Martin reunites with Julia, and together they make contact with the West German journalist – but the Stasi is watching…