Kara plans an expedition to find Ubar. She contacts Omaha Dunn, Safia's former fiancee and a noted expert on the Middle East and antiquities as well (and an adventurer, in a very obvious homage of sorts to Indiana Jones) and asks him to help them. The U.S. government pulls some strings and Painter ends up Kara's uninvited - and unwelcome - guest for the duration of the trip. Many more unexpected perils and adventures await once they arrive, however, as they are confronted not only by Cassandra's competing force, bent on discovering the secrets of Ubar, but also by a group of women who have the ability to seemingly disappear at will. The expeditionary team is separated after one of Cassandra's attacks, which leaves her in possession of Safia and the heart (and with Painter, Kara, Omaha and the others in hot pursuit).

As they push toward Ubar, they learn more of this ancient society of women who haunt the deserted mountains, a group with mysterious ties to the woman who once ruled Ubar: the Queen of Sheba. This militant order of Amazonian warriors have strange abilities: they are capable of something akin to invisibility, and can also propagate without men, via a process called "parthenogenesis," which is a form of asexual reproduction. This is where Rollins' advanced technology comes in: he manages to explain much of his "mystery" through the use of arcane scientific concepts such as antimater and cellular "buckyballs." In one sense, it's rather like a Scooby-Doo episode for grown-ups: he presents all these seemingly magical forces, and then has a scientist come along and explain it all, pulling the mask off the villain's head and saying, "See, it was just so-and-so all along." While it is interesting (if somewhat farfetched), it also starts to become somewhat tedious after a bit as he finds it necessary to present so much expository narration (usually through dialogue) to actually explain his "magical" technology to the reader.

The upshot of the whole thing is that they suspect there is a huge cache of antimatter hidden (and somehow held in a non-explosive state) beneath the desert in the ruins of the fabled city of Ubar. Not only would such a find be an incredible source of energy (and a potential weapon), but there is also a fear that there might be some sort of trigger or "detonator" associated with the storage, and that the Ubar antimatter might explode much like the London statue did, only on a much larger (and more devastating) scale.