After two years of working for the London Police, which ended in severe mental and physical trauma, Carol Jordan returns to Bradfield, where she is offered to lead a team investigating particularly serious crimes. Just at this time, a murder is committed that absolutely fits into a series of murders two years ago, for which Derek Tyler was convicted and imprisoned in a special hospital. Tony Hill, a talented clinical psychologist who followed Carol to Bradfield, gets a job at a special hospital, and Derek becomes his first patient. Tony claims that no two forms of insanity are the same, and therefore either Derek is innocent, or someone is trying to get him out of the mental hospital by confusing the police.