It is the autumn of 1944. Allied armies are sweeping through France towards Germany. A British
Lockheed Hudson has been damaged in aerial combat with a German
Messerschmitt, with both aircraft ditching in the
North Sea, twenty miles off the Dutch coast. The four crew from the British aircraft are unable to send a complete mayday alert, although a signal fragment reaches England. Among them is Air Commodore Waltby who has a briefcase containing secret German plans for the successor to the
V1 and
V2. Flight Sergeant Mackay assumes a leading role in the rescue dinghy, tying everyone together to prevent anyone falling overboard, and sharing his boots with the pilot despite the cold. As the weather closes in and a freezing cold night descends, aircraft suspend their search, leaving the now waterlogged dinghy to face the sea alone. Waltby orders the others that if he dies, they must get the briefcase to London or throw it overboard should they face capture. An
RAF Air Sea Rescue sea launch joins the search. Commanded by Flying Officer Treherne, Launch 2561, or "Sixty One" in radio signals, struggles against the bad weather, mechanical problems and a fire in the galley. Second in command, Flight Sergeant Singsby dominates the crew, playing a benevolent but demanding hand with the questionable seamanship of the junior ranks. On the second day, updated intelligence about the dinghy's likely location is received from the downed German Messerschmitt pilot, whom the RAF has rescued. RAF Air Sea Rescue is now aware the dinghy has drifted inshore, far from its ditching point. As the weather clears, "Sixty One" sights the dinghy and approaches it under fire from enemy shore batteries and through a mine field. Launch 2561 safely returns to England where the briefcase with secret documents is delivered. An injured Flying Officer Treherne and Flight Sergeant Mackay are applauded by senior officers. ==Cast==