"The Fighting 69th" is a World War I regiment consisting mostly of New York-Irish soldiers. Jerry Plunkett is the cockiest member of a cocky crew. Jerry is a scrappy fellow who looks out only for himself. The officers and enlisted of the regiment do their best to instill discipline in Plunkett, and the chaplain, Father Duffy, tries to make Plunkett see the greater good. None of them seem to succeed. In the trenches, Plunkett acts selfishly and cowardly, eventually costing the lives of many of his fellow soldiers. A final act of cowardice leads to terrible consequences, but Plunkett sees in them a chance to redeem himself.