A first novel that features familiar figures and situations but analyzes them with intense psychological understanding and moments of real literary flair. Yes, it's the return of the serial killer going one-on-one with a female shrink specializing in the habits and behavior of mass murderers. This serial bloodletter turns out to be quite possibly the world's top nut, with some 130 dead victims hidden in a cave. Meanwhile, Dr. Helen Myrer, a widow in her late 40s, has been fighting Albany over massive cuts in aid for the mentally ill. Having three weeks free, she goes to an isolated cabin in the New Hampshire woods. As she enters, she confronts a figure in a stocking mask, holding a knife, waiting in the pantry, and things pretty much go downhill from there. The mass murderer turns out to be her neighbor in the woods, Kevin McCallum. There is, of course, an obligatory flight sequence through that cave of corpses, serving as the novel's extended climax. During an interim of torture and terror, we receive material about Helen's family that proves even more interesting than her present plight. Using her training, the naked Helen tries to enter the mind of her attacker and persuade him that she can help him overcome his various triggering traumas. But loathsome Kevin's unique symptoms lie beyond the scope of her diagnostic and statistical manual: ``For the first time in her life she was beginning to entertain the notion that evil could exist in a state that might in some way be intractable to science.'' As he's chasing her through the cave, Helen realizes that ``this was the interior of the man, his unconscious mind carved into the earth.'' Matthews comes up with the spidery, slithery, squishy goods in a predictable but nonetheless thrilling showdown. Nail-biting twists that challenge your jaw muscles.