Amidst Commemoration Night festivities at Beaufort College, Oxford, chaos erupts twice—the first time during the playing of a prank using Professor Benchley's newly acquired mummy, the late King Pepy I, and the second time when a fire consumes the Bursary, coincidentally the building where Benchley resides. This combination of events results in a mystery: the disappearance of either Benchley or the mummy. Despite the coroner's ruling of accidental death for the professor, only one corpse is recovered among the ashes at the scene.

Professors Sargent and Considine cannot let the matter rest with this verdict and go sleuthing, using all the scholarly know-how of their academic specialties and they find themselves entangled in a web of very unusual circumstances.