Four wealthy women, sailing from New York to Genoa aboard the Italian luxury liner Beatrice Cenci:
Mrs. Abercrombie, regal, imperious, and accustomed to giving orders, but confined to a wheelchair by a heart attack. Valerie Meadows, her nurse companion, equally, if less publicly, rich; a woman with a past. Gloria Grandi Pontini, a self-made career woman, with a husband who's jealous enough to kill. Susan Emery, a young Englishwoman who soon will be fabulously wealthy, if she lives long enough to gain her inheritance.
Then there's Butler, a secretive chain-smoker with a blurry newspaper photograph, and a contract for murder.

As the passengers frolic in the sumptuous elegance of her staterooms and cabarets, a killer stalks the decks under a full moon.