On their mission to Navarone Major Mallory and Sergeant Miller thought that there was traitor in their group, whom they thought was executed. But it seems that not only was he not executed, and he was not a traitor but a German spy. Whom intelligence believes made it to Yugoslavia and is now with the Partisans. So, Mallory and Miller being the only ones who can positively identify him, are sent along with a unit called Force 10, which is led by Colonel Barnsby, who objects to their presence. It seems that Force 10 has a mission of their own which Mallory and Miller know nothing about. When their plane is shot and most of the team is killed, they mistakenly believe that some of the locals they meet are Partisans when in fact they are German Allies. They are taken prisoner, and have to convince the German commander that they are not spies or else they will be killed - and there is still an important bridge to be blown up.