Frustrated with seeing good young men die under his command, Sgt. McGrath (Robert Webber) of the U.S. Marine Corps decides to pick a group of "expendable" men from the brig for a dangerous mission during the Korean War. Behind enemy lines, the motley gang of misfits and malcontents comes across a group of Catholic schoolgirls and their nun chaperone (Anna Sten) whose bus has been hit in an airstrike. The Marines proceed toward their objective with the girls in tow, while one man (Leo Gordon) stirs dissension in the ranks.