Kim Beckett, the golden welder who answers New York science reporter Lynn Hershey's personal ad, would be Mr. Right if he weren't a murderer: a premise first-novelist Neimark can't decide whether to play for psychological thrills or the cheaper kind. At first Lynn, still scarred by her older brother Cob's disappearance 14 years ago (a drifter, he still writes from time to time without ever giving an address), finds that Kim's revelation-- that he killed Puerto Rican doper (wholesale) Raphael Nadal--makes him even more attractively intense. She recalls their bouts of lovemaking in scorching detail and gets into impassioned technical discussions (``cunnilingus is a consolation prize'') with her old roommate Sherry and Sherry's neighbor Dana. Meanwhile, though, alternating chapters are stretching for something more ambitious than another helping of sex and power in the 90's. Lynn labors to come to terms with Kim's crime--a task made nearly impossible by unconvincing plot twists (Nadal's girlfriend Katie Gonne and his avenging nephew Popi both turn up in New York; Kim drops out of sight; Lynn lets Popi spirit her off for a surrealistic interlude in Puerto Rico) and Neimark's tendency, following other I-Slept-With-a-Killer fantasies, to substitute wide- eyed lucubrations for insight (a tendency kicked off by the novel's opening line: ``I'm in love with a murderer''). Eventually, the pulpy underside of plot and tone swallows up the novel. Too one-note hysterical for its loftier ambitions, too inconclusive to work as pulp. The early chapters, though, have distinct possibilities as a pillow book.