Picking the wrong photo from an escort service's book sends Philadelphia ad exec Ruth Lasseter careening into a nightmare of murder and obsession. Ruth's just looking for somebody presentable to bring to an office party that her lover and his suspicious wife will be attending. But she gets more, much more, after her subsequent one-night stand with good-looking Tim Hagan. Tim is evidently so besotted with Ruth that he won't let her break it off--and if she could look into his past, she'd see how badly he handles rejection. In what seems like the crest of her terror, quietly demented Tim kidnaps her from her office; but although she's rescued by security guard Aidan Kincannon, her nightmare only deepens. A year later, even after the police have called her and Aidan to identify Tim's body (fat lot they know), she's still convinced he's out there watching her--and of course she's right. Working with Aidan and against the police and the feds--who want to deport her to Britain: she's lost the job that guaranteed her status, and there's the little matter of an unlicensed gun--she traces her tormentor to his sordid roots in Louisiana. Only now does Gallagher (Nightmare, with Angel, 1993) allow the slam-bang pace of his story to flag, as he labors to fill in dysfunctional family background that makes Tim more human but distinctly less intimidating. (It doesn't help his reputation that some of his victims, like Tim himself, show a lamentably anticlimactic disinclination to stay dead.) This modulation, though, prepares for an original and chilling payoff: Ruth, echoing Tim's original mothlike attraction to her, becomes so obsessed with him--with finding him, killing him, dying together with him--that it begins to look as if the real danger is to anybody who might get in her way. A satisfyingly twisty suspenser with a truly menacing villain.