George D'Arcy and Tim Ryan, rival leaders of neighborhood gangs, become stokers and watertenders on a U. S. battleship during the World War. For a time, their rivalry over politics, social affairs, and the same girl--Rose--is held in check by discipline, but their parish priest, Father Joe, the ship's chaplain, finally decides to let them fight it out in the ring. Their fight is interrupted, however, by a submarine attack, which is repelled. After the war the feud continues until narcotics smugglers kill one of George's brothers and shoot Tim's buddy; together they storm the smugglers' stronghold and blow up their submarine. Later, under the supervision of Father Joe, a fight is staged, and George is the victor.