Just as Pam and Jerry North stepped off the pages of The New Yorker to meet murder 50 years ago, thirtysomething sprouts a detective plot in this first novel by and about a pair of physicians. Dr. Archer Rush Montana, head of infection control at United Hospitals of Pennsylvania, is baffled when millionaire philanthropist Vanning Epps dies shortly after being admitted to UHOP with pneumonia, and his bewilderment turns to alarm when his wife Molly points out that a suspiciously large number of hospital personnel have died prematurely in recent months and suggests that Epps's death is part of a pattern. She's wrong--all those other deaths, amazingly, turn out to be (1) a series of stress-related suicides and (2) completely unrelated to Epps's death--but Epps has indeed been murdered, by someone who managed to infect him with AIDS virus. (Another incredible coincidence is that straight-arrow Epps turns out to have had a homosexual affair years ago, but with someone who has nothing to do with the case.) At the request of Epps's hardheaded, fairy-godmother widow Grace, Monty and Molly brave the opposition of Monty's self-protective boss Dr. Perrin Larraby and pettish blood-bank director Dr. Rudolph Low to find out just how and why Epps got his fatal dose. The suspects are few and anemically developed, but to compensate there's bright detail about the hectic pace of Monty's job, Molly's expertise as a rower, and the wonderfully cute Montana kids and dog. Bloodless.