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 desperately needed water.