In the summer of 1923, the Honourable Daisy Dalrymple makes what should an uneventful research trip to the Museum of Natural History with her nephew Derek and her soon-to-be step-daughter Belinda in tow. But as she interviews the various curators for her article on the museums of London, she soon discovers that the Museum of Natural History is a hothouse of professional rivalry and jealousy, particularly between Dr. Smith Woodward, the Keeper of Geology - responsible for the fossil collection, and Dr. Pettigrew, the Keeper of Minerology - responsible for the Museum's fabulous gem collection. On a later trip, as closing time nears, Daisy hears two voices followed by a tremendous crash and rushes into the next hall to discover Dr. Pettigrew dead - murdered amidst a pile of dinosaur bones.