When Dr. Martin (Robert Powell) arrives at the Dunsmoor Asylum for the incurably insane, he expects to be interviewed by asylum director Dr. Starr. Instead he is met by Dr. Rutherford (Patrick Magee), who explains that Dr. Starr had suffered a mental breakdown and now is one of the patients.

Dr. Rutherford decides that if Martin can deduce which one is really Dr. Starr, then he will be given the position.

Is it Bonnie (Barbara Parkins), whose affair with a married man turns murderous? Is it Bruno (Barry Morse), a hardluck tailor visited by a mysterious stranger (Peter Cushing) with a blueprint and very special fabric for an unusual suit? Is it Barbara (Charlotte Rampling), accused of murdering her brother and her nurse but insisting that her friend Lucy (Britt Ekland) was responsible; Or is it Dr. Byron (Herbert Lom) who claims the ability to transfer collecting?

Robert Bloch (PSYCHO) wrote this quartet of tales that fit together to solve a mystery that serves as the catalyst for each segment. The setup has a doctor who is trying to become the new head of an asylum has to figure which one of four patients held the position previously before he is allowed to take over. So, one by one, each patient tells their story, leading to an unexpected finale. This is just about the best of the sub-genre of anthology horror films, as each segment works both as a stand alone film, and as part of the overall mystery. AKA "House of Crazies."