故事讲述的是一个极度危险的精神病人从医院逃出，与常人无异般地在街上随意出入。在杀死一名女子后警方在医生的配合下终于找到了线索，与嫌犯展开了一场貌不惊人却暗藏乾坤的搏斗。

Following the success of his first three films, Dario Argento curated and produced a series of four medium-length films, each approximately an hour long, for RAI. In addition to presenting each episode, the director himself directed one of them, The Streetcar, also taking over from Roberto Pariante as director of Eyewitness. The other two films were directed by Luigi Cozzi, a collaborator of Argento's, and Mario Foglietti.

Roberto, a drummer in a rock band, keeps receiving weird phone calls and being followed by a mysterious man. One night he manages to catch up with his persecutor and tries to get him to talk but in the ensuing struggle he accidentally stabs him. He runs away, but he understands his troubles have just begun when the following day he receives an envelope with photos of him killing the man. Someone is killing all his friends and trying to frame him for the murders...