O tenente Joe Rossi é primeiro oficial num Navio da Liberdade em um grande comboio de Halifax para Murmansk. Depois de submarinos alemães atacarem o comboio seu navio se separa e está indo sozinho para Murmansk. Apesar dos ataques de aviões e submarinos alemães ele luta para levar o navio em segurança para Murmansk.
Humphrey Bogart heads a decent cast in this exciting compendium of tales of maritime courage and determination during WWII. Initially he serves under Raymond Massey ("Capt. Jarvis") on a tanker but when that falls foul of an U-boat, they find themselves stranded on a raft and left to the elements by it's particularly unpleasant Captain. Some while later, the team reunite to escort a convoy to Murmansk and encounter the same submarine and a deadly cat-and-mouse game ensues. It is bit too long, but Massey, Bogart alongside the always reliable Alan Hale manage to bang the drum successfully for the most part, demonstrating the prowess of these brave sailors facing the elements and Nazis as they tried to keep the supply lines open. The cinematography is tautly presented and effective, as are the effects and the flag-waving is a bit more sophisticated than in many similar propaganda exercises - tragedy and success occur giving the film a certain degree of realism and plausibility.
