After the fall of the Libyan city of Tobruk, Sergeant Joe Gunn (Humphrey Bogart) and his crew–‘Waco’ Hoyt (Bruce Bennet), Fred Clarkson (Lloyd Bridges) and Jimmy Doyle (Dan Duryea)–retreat in their tank across the Sahara. Along the way they pick-up six Allied stragglers and Tambul (Rex Ingram), a Sudanese corporal, and his Italian prisoner. Tambul directs the group to a desert fortress, where they hope to find desperately needed water. A detachment of German soldiers arrives and attempts to barter food for water, but Gunn and his followers refuse. When the Germans attack, Gunn leads his desert-weary men in a desperate battle, hoping that British reinforcements can arrive in time.