Marc Borgmann, Hanno Koffler, is a young police officer-in-training in a riot-control unit who struggles at the academy, lagging behind his peers in physical tests. He clashes with his roommate Kay Engel, Max Riemelt, during a tense training exercise, but after Marc apologizes for his aggression they become friends and start jogging together regularly.
During one of these runs, Kay kisses Marc after sharing a marijuana cigarette, and Kay reassures him that it was a joke. On a subsequent jog the two kiss again, and Kay gives him a handjob, deepening the tension between their professional duties and private desires.
Kay is later transferred into Marc's unit to fill a vacancy, and Marc finds it difficult to ignore him. Kay shows up with a colleague at a bowling alley where Marc and his family are spending an afternoon, and he is introduced to Bettina Bischoff, Katharina Schüttler, Marc's pregnant longtime girlfriend. Marc tries to stay faithful to Bettina and forget about Kay, but he keeps returning to the jogging trail where Kay waits. The pair have sex in the rain, and Bettina grows suspicious as Marc continues to have intimate encounters with Kay under the pretense of night shifts; Kay also gives him a key to his apartment. Marc laments that he is less able to perform with Bettina, in part due to the changes around her pregnancy.
Later, Marc and Kay go to a gay bar, where Marc takes ecstasy. The morning after, Bettina rebuffs him and asks if he is seeing another woman, which he denies. Bettina eventually gives birth to their son, and Marc tries to cut Kay out of his life; however, Kay reaches out, leading to a tense reunion that culminates in a kiss that both men struggle to justify.
The situation escalates when Kay defends himself after an altercation with a fellow officer, Gregor Limpinski, Shenja Lacher in a heated moment. Marc goes to Kay’s apartment and confronts him about the fallout, even as Kay calls Marc selfish yet insists he loves him and is not sleeping with anyone else. Kay later visits Marc in the hospital, and the two share a kiss that Marc's mother, Inge Borgmann, Maren Kroymann, quietly witnesses. The moment deepens the emotional stakes and triggers a sharp argument that drives a wedge between Marc and his family.
At a party that Bettina invites him to, Marc’s parents urge him to stay away from Kay because of the new family he has formed. Marc, hearing this, tells Kay to leave the gathering and to move on. He later goes to Kay’s apartment to find Kay’s face bruised after another confrontation; Marc suggests Kay transfer to another unit, and Kay asks about their future together. Marc returns Kay’s apartment key and departs, signaling a definitive turn in their clandestine relationship.
Back home, Bettina returns with their son, but emotional distance remains. Bettina has discovered that Marc has lied about working night shifts and wants him out of their life. Marc travels to Frank Richter’s house, where he finally confesses his affair with Kay, played by Oliver Bröcker. Bettina comes back, bringing their son, but the cracks between them widen and a sense of impending separation hangs over the household.
Marc tries to visit Kay at his apartment, only to find it empty as Kay has moved out of the unit without notice. Limpinski tests Marc with provocation about his relationship, and Marc taunts him in return. Frank witnesses the tension and hints that Limpinski may be fired, underscoring the precariousness of the squad’s environment.
In the end, Marc seeks solace in the same space where his journey began. He goes to the gay bar alone, where he initiates contact with another man but ultimately rebuffs him. Returning to the house, Marc and Bettina acknowledge that their relationship cannot continue as before. The film closes with Marc back at the academy, running on the same track as in the opening scene, but this time he pulls ahead, running alone and carrying the weight of his choices.
