影片讲述二战初期，由37支盟军船只组成的护航舰队在欧内斯特·克劳斯（汤姆·汉克斯饰）舰长率领的一艘美国驱逐舰指挥下，穿越险恶的北大西洋，同时还要与德国U型潜艇狼群的周旋。Based upon the novel "The Good Shepherd" by C S Forester, this is the thrilling story of the leader of an Allied convoy crossing the North Atlantic in 1942 as he faces relentless attack by a Nazi submarine wolf pack. The leader of the convoy's destroyer screen is a US Navy commander making his first Atlantic crossing. The story focuses on the his command responsibility as he fights the cold, the relentless night, the brutal sea and his deep fatigue as he chases down the attacking submarines in the deadly game of cat and mouse. The exciting story, a thrilling ride-along with the beleaguered captain, so deeply portrays the elements of battle command that for a long period of time the book was used as a text at the US Naval Academy.