P.C. Hawke and his partner-in-sleuthing, Mackenzie, are shocked to learn that their friend Tom is accused of murdering the chief biologist at the Museum of Natural History. Unable to believe Tom would be capable of such a crime, P.C. and Mackenzie dig deeper, discovering at the heart of the mystery a world-famous necklace, an anthropologist trained in hypnosis, and a fat hairy tarantula named Aristotle.