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 (the living descendant of the pharaoh's bloodline) is charged by the Priesthood to overthrow the supposed impostor Cleopatra, drive out the Greeks and 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. Haggard's portrait of Cleopatra is quite stunning, revealing her wit, her treachery, and her overwhelming presence. All of the characters are mixtures of good and evil, and evoke both sympathy and loathing. While much of the material on ancient Egyptian ritual is overdone, the often brilliant dialogue and the fateful interactions between the principal characters make the book quite unforgettable in comparison to Haggard's better known but more conventional adventure novels. The character of Mark Antony, introduced in the later part of the book, is fleeting and lacks importance, though historically it seems that the book has some importance as the references made are based on facts about the romance between Cleopatra and Mark Antony and the fall of both from power.Cleopatra goes unrecognized in most discussions of Haggard—perhaps because of its stilted language.
Boucher and McComas gave the novel a mixed review, saying that it combined "a not always believable portrait" of its title heroine with a "fascinating, wholly convincing" story line.