"Williamson's artificial creatures are brilliant as always....Lush descriptions and a refreshingly brisk pace buoy the novel...."--Publishers Weekly

"Williamson's combination of SF technological inventiveness and heroic quest is surprisingly successful, offering a neat origin story for humanity, to boot."--Booklist

A dark mystery has been buried beneath the sands of the Sahara for eons. In a basement in New Mexico, four poker buddies find reason to believe that a startling secret is out there, and these four amateur adventurers are about to uncover it.

Curiosity propels mild-mannered professor Will and his three friends to the Sahara to excavate a site where radar has detected trilithic stones hidden beneath the sand. There they stumble upon an ancient artifact that will change their lives--and the world--forever: a gateway between planets, linking Earth to distant worlds where they will discover wonders and terrors beyond imagining. Now each traveler must play a crucial role in unraveling an ancient mystery, the solution to which may reveal the true origins of the human race--if they can survive the journey back to Earth.