For young detective Aggie Morton and her friend Hector, an opportunity to dig up fossils becomes even more thrilling when a corpse washes ashore.

After an invigorating but not exactly restful trip to a Yorkshire spa during which she survived a near brush with death and foiled a murderer, aspiring writer Aggie Morton and her friend Hector are thrilled to have the opportunity to stay at a camp by the sea and watch real paleontologists at work. The famed husband and wife team of the Blenningham-Crewes are about to become even more famous with the recovery of the fossilized bones of an ichthyosaur from the sea by Lyme Regis. This news has already caught the attention of an American millionaire, a British museum and a traveling circus owner, who each want the bones for their own collections. Tensions are running high throughout the camp, from the cook, to the collectors, to the Blenningham-Crewes themselves, and become downright dangerous after Aggie and Hector make a discovery of their own: a body on the beach. Not a fossil, but a human body.