Billed as one of the most violent movies ever when it came out, it is quite tame by today's standards.
Joe Collins (Burt Lancaster) is released from solitary back to the general prison population. Joe is head of one of the main prison gangs. The warden is an old exhausted man, who has been in the position years. The prison is really run by Munsey (Hume Cronyn) a sadistic head guard.
Joe wants to plan an escape, but needs help from Gallagher (Charles Pickford) another leader among the prisoners. Gallagher refuses, he has been secretly working with the warden to keep order in the prison. Gallagher has been promised the warden will get him paroled soon.
Joe goes to the infirmary, while his gang kills the snitch who got him put in solitary. The alcoholic doctor knows Joe called in the hit, since Joe keeps making a point of asking everyone the time to establish his alibi of being in the infirmary while the inmate was killed. The drunk doctor supports the prisoners against the guards. Munsey taunts and torments another inmate so much, that the man kills himself.
With the 2 deaths, the prison is put on lockdown. Gallagher is told that his parole is off due to this. Gallagher decides to help Joe escape. While they prepare the escape, we see in flashbacks why each man is in prison. In each case, there was a woman who drove him to crime. As they are initiating their escape, an announcement comes over the speakers that the warden is resigning and Munsey is the new warden. The prisoners riot.
Munsey instructs the guards to shoot to kill the rioters and the escaping prisoners. Joe makes it up a guard tower, where he throws Munsey to his death. Joe dies from his injuries. None of the prisoners escape.