Someone is messing with the Museum of Natural History, mixing human models from the new Pleistocene Megafauna in with the dinosaur exhibits, and Wilson Kipper, whose mother works in the museum as a paleontologist, and his friends are determined to find out who is responsible for the anti-science vandalism--the new professor, her nasty daughter, or someone else entirely.

School's out -- Theories -- The painted hunter -- Dr. Snapper -- Heavy objects -- Why, how, and when? -- Time travel -- Ruthie's righteous rage -- Crowds -- Alibi for Alvin -- Kitchen crook -- The new girl.