Gossip reporter Rain Morgan (Death on Widow's Walk) and her cartoonist lover Oliver West, both of the London Daily Post, have wangled a plum assignment--a trip to the French Riviera to do a story on painter-sculptor Sabine Jourdain, only remaining acolyte of famed, aging painter Marius Durance. Once settled in a borrowed apartment in Antibes, Rain tries to make contact with her subject, going first to the Villa Fiesole to meet Sabine's English friend Barbara Coleman, finding only a bloody handprint on the gate and no one home. Then a note from American art-dealer Benedict Joseph brings Rain to the lush, chartered yacht Jonquil, where the dinner guests include Joseph's wife Merlyn, Nice gallery-owner Phillipe Maurin, the enfeebled Durance himself, and untalkative but still vigorous Sabine. A second appointment is made for the following night--but that meeting never happens. Sabine is found shot to death, and Rain now concentrates on finding out why and by whom. There are endless meetings, messages, menaces, crossed signals, and red herrings while Oliver amuses himself on the beach and Rain nearly gets herself killed. The murderer, when he finally surfaces, is reasonably convincing. The drug-related subplot isn't. A cluttered, wordy narrative and myriad paper-thin, eccentricity-laden characters don't dispel the boredom that casts an early pall on Guilty Knowledge.