The Storm Knight — Frederick E. Smith

By the author of 633 Squadron... Steve Brand, a young Canadian skin diver on holiday in Norway, unwittingly brings the cold touch of fear to the tiny village of Indal, still bitter and resentful of a war time betrayal. To help a lovely girl prove her father's innocence of treachery, Steve joins forces with the tempestuous Steen Ericson in an underwater partnership that dices with death. A malignant, dangerous wreck held the secret of a bloody massacre, and it was there, fathoms deep in Blood Fjord, that nightmare became reality.