Corpses may abound--but neither the violence nor the mystery seems remotely real in this pallid debut for retired-teacher Sister Mary Helen, dedicated reader of detective fiction. Now living at a Catholic women's college in San Francisco, Sister Mary Helen is exposed to a non-literary murder, when the body of unpopular Professor Villanueva is found. The cops promptly arrest Leonel de Silva, one of the college's many Portuguese workers, but quickly release him--even before another body surfaces: that of missing Joanna Aires, sister of the professor's secretary Marina. . .and author of a now-unfindable thesis on recent Portuguese immigrants. So it soon becomes clear to Sister Mary Helen, listening and watching, that the dead professor's respectable-looking charity (he sponsored many of those immigrants) is behind the crime wave. And she eventually leads the police to more bodies--and an uncompelling rationale for all the mayhem. In more experienced hands this plot might have built in interest and suspense. Here, alas, it's twittered into limp collapse amid an atmosphere of bland detachment--though first-novelist O'Marie (herself a nun) does better by the romance between cop Kate Murphy and her live-in Italian lover.