Based on Charles Cunat's novel, Surcouf tells a romanticized version of the life story of Robert Surcouf, a French privateer and slave trader who operated in the Indian Ocean from the end of the 18th century to the beginning of the 19th century.

The story is set in Berlin at the beginning of the 20th century. The members of a singing group live in poor conditions in a dilapidated building. When the manager of the property is murdered, Peter and Paul, both members of the singing group, become suspects in the murder. When they return from a performance, the police are waiting for them to take them in for questioning. Since Paul is the most likely perpetrator according to the investigation, he is arrested immediately.

Four classmates decide to perform a love song that their friend, Pierre, composed for Marie. Novac, another admirer of Marie, is murdered. Pierre suspects one of the four of being the killer, but incriminates himself, believing that Marie was in love with the killer.