A lively plot involving a missing black diamond is weakened by sappy characters in this Regency romance by the author of Wishes in the Wind. When Slayde Huntley, Earl of Pembourne, receives notes demanding ransom for his missing sister, he hands the costly but possibly accursed jewel over to a pirate. He quickly discovers that the woman delivered to him is a kidnapped look-alike, and that his sister has been gallivanting about London unharmed. Courtney Johnston, the daughter of a sea captain, is stunned to awaken in the earl's home and to realize that her father may be dead. She and Slayde team up to catch the pirate, who may also be linked to the slayings of the earl's parents ten years earlier. Although readers may enjoy unraveling the trail of clues, the central romance bogs down as the characters talk about their feelings at tiresome length and in cliched terms (""You've spent your whole life being strong for others. 'Tis about time you allowed someone to be strong for you. Thank you for letting me be that someone--even for a fleeting moment""). (Feb.) FYI: A sequel, The Black Diamond, will be published in late '97.