After the fall of the Libyan city of Tobruk, Sergeant Joe Gunn (Humphrey Bogart) and his crew - "Waco" Hoyt (Bruce Bennett), 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 desparately 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 desparate battle, hoping that British reinforcements can arrive in time.