Based on a stage play of the same name, it's typical Lumet stage play adaptation to film that retains much of a stage play "feel" to it. The film centers around the blood feud between Jerome Malley (James Mason) and Joseph Dobbs (Robert Preston) with a newcomer PE teacher and sports coach to the school Paul Reis (Beau Bridges) getting caught in the middle of the feud between the two, each one attempting to get him to side with him. Malley (Mason) repeatedly accuses Dobbs (Preston) of subterfuge and maliciously going things to malign his character. Tension gradually builds through the entire film until it reaches a climactic head at the end, and it won't be what most expect. A first rate psychological thriller, it's like most stage plays, longer on dialog and shorter on action as there are limits to how much "action" one can have on a stage. That's OK as this is a cerebral thriller, not an action thriller.