Credible Threat

California PI Jeri Howard, seen last in Nobody's Child, takes a deliciously suspicion-saturated interest in everyone around in her latest adventure. That doubting stance makes the best part of this tale, which begins with harassing phone calls and some flattened flora and is strong-armed to a gun-waving finale. Vicki Vernon, the daughter of Jeri's ex-husband, calls for help when she and her housemates, all U.C. Berkeley students being threatened by menacing phone calls, find their garden has been trashed. The group of eight offers Jeri a wealth of possible leads: Vicki and another are pestered by an obnoxious man they refuse to date; one encounters ""frightening people"" when she volunteers at an abortion clinic; another works at a center for battered women. A few, Jeri learns in her probing, have omitted bits of their history when talking with her. She hasn't made much headway when a pipe bomb is tossed through the front window. Leaving most of the college crowd behind, Dawson sets a related mystery behind the current danger, one that hinges on an old unsolved homicide case that Jeri investigated eight years earlier. This plot twist and a sprinkle of coincidence heightens the narrative's melodrama but, despite the title, reduces its believability. (Nov.)