Something odd is going on in Adams Memorial Hospital's mental ward, but the patients aren't the cause. A statistically significant number of the mental patients check out of the hospital and then disappear--forever. Only Sharon Francis, a feisty second-year psychiatric resident, notices that anything strange is happening, and she fights (literally) to solve the mystery. She must deal with disbelief, hostile doctors, a masked attacker, and even the possibility of her own insanity to expose the criminals. If the idea of a female doctor ferreting out a medical plot all alone sounds vaguely familiar, that's because this book is similar to Robin Cook's Coma ( LJ 5/15/77). As with Cook, some of Spruill's story lines stretch credibility, but the relentlessly suspenseful plot and the undercurrent of terror will keep readers turning the pages quickly until the very end. Literary Guild and Doubleday Book Club selections.-- Rebecca House Stankowski, Purdue Univ. Calumet Lib., Hammond, Ind.