Tunisia 1943 - the Allies' advance is halted by determined Axis forces. The 8th Army has no choice but to outflank the enemy along their impenetrable Mareth line in the hellish Matmata hills. On a mission to safeguard this movement, Captain Tom Caine's SAS patrol is diverted by a strange emergency signal that draws them to a derelict aircraft and a mysterious black box. Besieged by a Nazi Death's Head unit intent on retrieving the box and betrayed by a comrade who steals it, Caine must make a choice. Should he pursue the stolen object or stick to his original task and face almost certain death? The entire campaign rests on his decision.