Charles Williams - And the Deep Blue Sea (Signet edition)

First published by Viking Press (hardback) in 1971. This first paperback edition from Signet (Q4515) is dated March 1971. Cover art by Blossom??

Back cover synopsis: "When the S.S. Leander hauled Harry Goddard out of the freezing waters of the Pacific, he thought his troubles were over - but he was dead wrong. For what appeared to be a cruise ship en route to the Philippines turned out to be the board on which a lethal game was being played - a game of international intrigue, double deception, and multiple murder, where the stakes were sex and power and the price of one wrong move was certain death..."