A "rehabilitated" serial killer appears to be on the loose again in this debut romantic suspense novel from Morgan (who writes romances as Colleen Faulkner: Shocking Request, etc.). Horrors from the past invade the idyllic beachfront home of newly divorced writer Sydney MacGregor and her feisty teenaged daughter when Sydney learns that her twin sister's murderer, serial killer Charles Eshey, has been released. Her fears intensify after the child of a fellow survivor disappears. Thirty years earlier, Sydney's testimony locked up the Twin Murderer, whose MO involved killing one twin and leaving the other alive. Now Sydney fears that the newly released Eshey, a twin who fathered twins and killed his own brother simply because they "couldn't both exist on this earth," will target her child. The suspense wanes while Sydney tries to prove that Eshey, a wheezy old ex-con with a heart condition, is still dangerous. Desperate, she teams up with true crime author Marshall King. Meanwhile, an unfortunately named lesbian FBI agent, Jessica Manlove, pursues Eshey on her own. All the threads come together in a taut, surprising climax, but even this final twist fails to offset the book's sluggish middle and tepid romance. (Aug.)