Legend has it that if the famous Barbary Apes leave the Rock of Gibraltar, it's a sign that the British will lose control of it. During World War II, a British officer is put in charge of the apes. When he detects that the animals' morale is slipping, he hatches a plan to go behind the German lines to "kidnap" a new ape for his charges to lift their spirits before the Germans find out about their condition and use it as propaganda.

Squadron Leader Quint Munroe, an RAF pilot in World War II, has a hard time dealing with the presumed death in action of fellow Sq. Leader David 'Scotty' Scott, whose family practically raised him when he was orphaned, so they were like brothers. RAF Air Commodore Hufford has a crucial task for Quint, who is no longer serving in the squadron: a reconnaissance flight over the château de Charlon, a castle in occupied France, where the Nazis are probably developing a new generation of flying bombs; the defenses are indeed suspiciously tight. When analyzed, the photos show the castle grounds harbor an underground launching tunnel, and Quint gets a nearly impossible precision top-secret mission: select and train a team in only 10 days, when the French underground believes the first launch is planned, to 'aim' a new type of bouncing bomb into the tunnel, to blow up the whole Luftwaffe installation. Quint falls in love with Scotty's young widow Beth Scott, whose crippled brother, Flight ... Written by KGF Vissers