Athens, 4 May 1973. In the small hours, a pitiless and particularly aggressive killer stabs to death hapless Eleni Chalkia and manages to escape unseen. As the poor girl lies in a pool of blood, the police and shocked passers-by gather around her dead body, unable to fathom the murderer's motives. As a result, Captain Giannopoulos, of the local police department, struggles to shed light on the opaque mystery, interrogating several witnesses whose conflicting testimonies have caused the investigation to reach a standstill. Then, by a twist of fate, young Ioannis Zachos appears, an intelligent, schizophrenic psychopath plagued by fantasies of blood and murder, eager to confess his crimes. However, the question remains. Is violent John insane or not?