Hamburg, 1935. The anti-fascist Arnold Clasen (Uwe Kockisch) returns from a concentration camp and rejoins a resistance group. Since he is under surveillance, he keeps a low profile and avoids contact with his comrades. In the afternoons and evenings, he works as a projectionist at the Orion-Lichtspiele. Sometimes he meets with Renate (Jenny Gröllmann), whom he loves. She comes from a middle-class family but shares his political views. The isolation weighs heavily on him, and he seeks friendship with his contact, Walter (Michael Gwisdek). He wants to trust someone, but mistrust runs deep. In addition to the danger from outside, there is betrayal within their own ranks. There are arrests within the group, and Arnold begins to suspect that Walter is the traitor.