It's been downhill for Segal ever since Love Story, with the classicist turned pulp-master generally coming up with a good, commercial idea in each novel and them gumming it to death. Such is the fate of Doctors, which follows the careers of a number of M.D.s, Harvard '62, and begins promisingly, by exploring the rigors and black ironies of reed school--how it chews up our best and brightest and spits them out, how, as main character, Barney Livingston, says, doctors ""are the most vulnerable of human beings."" We watch as Barney and his neighbor from Brooklyn, the brilliant and beautiful Laura Castellano, suffer through their first year at Harvard, including suicide attempts, lousy cafeteria coffee, hair-raising competition, study aids turned drug addictions, and Barney's first pelvic exam. The two of them have always been best friends--nothing more--so when Laura marries a Boston Brahmin, that's okay by Barney. Meanwhile, their classmates are a wildly mixed lot: Seth Lazarus, a bumbling genius; Grete, the frigid Nordic bombshell (whom Barney keeps having wet dreams about); Bennett Landsmann, the black adopted son of wealthy Cleveland Jews, and many others. As they all battle out school together, their stories cohere, but once everyone disperses for residency, the novel flattens out. Barney becomes an NYC shrink and writer; Laura, an obstetrician who can't handle sexism in the hospital; Landsmann, a forensic lawyer; Seth, the defendant in a euthanasia case. And finally, after many romantic disasters for both, Laura and Barney figure out that they were meant for each other--which should have put a cap on things, except that Segal must get in one last jab, by having their baby almost succumb to an exotic infant disease. Segal's feeling for this material carries him through maybe 200 pages--the remaining 488 are fodder.