Why mess with success? Dog-trainer/p.i. Rachel Alexander's second case is so much like her fine debut (This Dog for Hire, 1996) that she could sue herself for plagiarism. Again there's a mysterious death--this time t'ai chi instructor Lisa Jacobs's alleged suicide--witnessed only by the victim's dog; again the stricken survivors are looking for an explanation for the inexplicable (why would got-it-all Lisa leave a note saying, ``I'm sorry. Lisa,'' and take a header out her window?); again Rachel hits the mean streets accompanied by her pit bull Dash. ``You won't learn anything worthwhile about Lisa by asking questions,'' Lisa's mentor and former boss Avi Ashkenasi tells Rachel. ``You must walk in her shoes.'' So as Rachel sweats to figure out which of Lisa's friends and students would've been most unhinged by her plans to move to China--and sweats too at the t'ai chi studio, the swimming pool, and the gym where she goes to ask all the questions she shouldn't--she wears Lisa's perfume and bracelet as well as her shoes, carries her keys, and beds her lover, half-Chinese swim coach Paul Wilcox. But her attempts to isolate a prime suspect fail when the front-runner gets killed--just like last time--clearing the way for another ton of moondust and (a sad innovation) an abrupt and arbitrary climax. Rachel's fans are advised to sit out her case of second- novel blues and wait for next year. If you missed her first, though, you may want to check out the most helpful canine sleuth since Asta.