Josef Dietrick lives with his self-absorbed mother, abusive step-father, and bullying step-brother, Marteen, in 1930s Berlin, Germany. When a brutal sexual attack at the hands of Marteen's friend, Tielo, sends Josef homeless into the streets, he is taken in by the kind-hearted Lucas and his sister Anke. Over time, gender-fluid Josef transforms into die blaue blume, the blue flower of Schoneberg, at one of the last underground cabarets for gay men and their entertainers, known as dolls.

A raid on the Rote Schwein leads to the capture of both Josef and Lucas who are violently carted off to Dachau, the notorious death camp. Here Josef is forced to choose between his kind-hearted lover Lucas or his now-Nazi childhood assaulter, Tielo. Forced into a form of slavery, Josef hatches a desperate plan to save both Lucas and himself forever. Will Josef choose self-preservation or to live authentically? Can he do both?