The story is set in the Ptolemaic era of ancient Egyptian history and revolves around the survival of a dynasty bloodline protected by the Priesthood of Isis. The main character Harmachis is charged by the Priesthood to overthrow the supposed impostor Cleopatra, drive out the Romans, and restore Egypt to its golden era.

As is the case with the majority of Haggard's works, the story draws heavily upon adventure and exotic concepts.

The story, told from the point of view of the Egyptian priest Harmachis, is recounted in biblical language, being in the form of papyrus scrolls found in a tomb.