Irish Colonel Charlie McPhearson has just had his platoon of twenty-eight slaughtered by German troops. Angered at his superiors for this suicide mission, he takes convicts on his next, along with fornicating American explosives technician Major Burke, to defuse underwater mines so that a commando squado can prepare for a June 10 invasion to destroy a tank gun. Because Colonel Ackerman, whose troops killed his last platoon, is the leader of the platoon in charge of the gun, McPhearson insists on trying to complete the commandos' mission.