The fourth case for Lt. Ben Tolliver, about linked murders in Manhattan, as Harvey attempts to upgrade his series begun with the overly predictable The Headsman (1991). A beautiful, wealthy blond walks into a jewelry store, asks to see a $100,000 necklace, then shoots the jeweler, his security guard, a customer, and finally herself. Reviewing the store's videotape, Tolliver can't find anything to go on besides the woman's unearthly calmness. The medical examiner eventually finds a Prozac-like substance (fluoxetine) in her blood, though that's a mere mood-enhancer. Then there are two more mysterious murders in the Village, on two different nights, as a young man walks up to a visitor, then to an antiques dealer, and stabs each to death through the breastbone. Some yellow capsules found by one of the bodies points to the same Prozac-derivative. Though Tolliver runs into blind alleys for over half the novel, the reader is introduced to Dr. Jonas Drang, a psychiatrist with a secret cellar lab for research on psychopharmaceuticals who has whipped up a swell new antidepressant made from rats' brain cells--but can't get the dosage right. The drug boosts the taker's confidence hugely, granting an amazing calm, but also releases the aggressiveness inherent in Dr. Drang's outsized Norwegian rats, mammals second in intelligence only to monkeys. When he does get it right, he'll go to Switzerland (he's already buying a house there) and give Eli Lilly a run for its money. Fact is, Dr. Drang's real objective is a drug that will allow armies to build up cadres of superbly aggressive soldiers. When Tolliver eventually gets too close to Dr. Drang, the good doctor gets in touch with his Village stabber. This fails, but Tolliver at last winds up bound in Dr. Drang's black-out cellar, being eaten alive by hungry rats . . . . Credible policework and fantasy sex give way to comic-book grue. Even so, a distinct series improvement.