An old ocean boarding vessel, the Castle Bay, is to blow up a secret Nazi base in the Norwegian mountains. Their careful plan goes awry almost immediately though, despite Sub-lieutenant Donald Cameron's knowledge of the treacherous coastline. The flotilla of dinghies meet a minefield & are ambushed, & only a handful of soldiers remain to make the attack. In the meantime, can the captain of the Castle Bay stand by after the rendezvous time when he is certain that the Germans are aware of his ship