1941: France has fallen; the Germans control every French port - In the English Channel German Schnell-boats frequently clash with British MTBs protecting the inshore trade. In the thick of the action is Lieutenant Lord Duncan Eversham, commanding an MTB flotilla. Duncans life is turned upside down when he rescues the survivors of a sinking merchantman, amongst whom is the mysterious American Rebecca Strong, engaged on a secret mission for the British Government . . .