During a concert in Berlin, a famous soloist claims that someone has stolen his valuable violin. Everyone finds it hard to believe him because there is an identical violin in his dressing room. However, the soloist insists. The mystery is to be solved by a dandy detective and a psychoanalyst. For the psychoanalyst, the solution is simple; it only requires a few sessions with the musician. However, a mysterious woman and a child prodigy make the detective suspect that the case is much more complex.

The first novel by Arthur Koestler (1905-1983) – and the only detective story he wrote together with his compatriot Andor Nemeth (1891-1953) – is an adventure with shocking twists that combines traditional detective plot with psychoanalysis.