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."