Close on the heels of the successful sheep experiment, this medical thriller jumps with engaging brio into the highly charged arena of human cloning. Ironically named 28-year-old summa Harvard grad Artie Singleton owns a successful San Francisco comic book and CD-ROM shop, which has accidentally become ""a magnet for the outrageous, the scorned, the academics, the trendy."" The bustling scene takes his mind off his mother's recent death from a particularly destructive case of Alzheimer's--until his equanimity is shattered by a mysterious letter from one of his mother's oldest friends. The letter informs Artie that he is one of 10 genetically identical clones. A computer junkie named Welinda Dupre, who's obsessed with a program called Autobiography, which allows ""nearly infinite constructions and revisions of a life story,"" is eager to help Artie track down his ""cellmates"" and the secret of their origins. The mission to find the brothers is derailed, though, after anonymous e-mails inform Artie that each brother with whom he has shared the secret has been found dead, an apparent suicide. Tension escalates as Artie and two other brothers--Les, a psychopathic recluse living in the High Sierras, and Tuna, a compulsive Las Vegas gambler who sees dollar signs in the genetic anomaly--race toward their fellow clones for radically different reasons and with potentially deadly results. Despite occasionally wooden dialogue (and forced, distracting engagements with the ethics of cloning) Burton (Doc-in-a-Box; Final Therapy) enlivens a faddish plot with fast pacing, credible characters and unpredictable plot twists. (Aug.) FYI: Before becoming a writer, Burton was Chief of Neurology at the University of California Mount Zion Medical Center.