Buck and his friends have managed to recover the blueprints of the Soviet supersonic bomber, but they're stuck on the wrong side of the Iron Curtain, with the entire Stasi hunting them. To maximise the chances of someone making it out, they decide to take different routes. But while Tumb and Sonny return to East Berlin with the blueprints, Buck chooses to go and destroy the existing prototypes on their base in Russia - what amounts to a suicide mission ...