When former Roman Legion Legate Gaius Marcus Linneus is reduced in rank to Centurion and banished by Emperor Marcus Aurelius to Tripolitania in Northern Africa, he finds his new command, a Shadow Legion, a reduced century of dishonored legionnaires, as much punishment as his dishonor. Castra-Augustus, a small fort in the southern Sahara, is under attack by an unseen enemy who takes soldiers at night, leaving only shredded clothing. He is determined to vanquish this enemy to regain his lost honor.
Gaius discovers an ancient city carved from solid rock half-buried by shifting sands. When Rashid, who claims to be a Berber salt merchant, arrives just after two more legionnaires disappear, Gaius questions him and learns the name of the ancient city – Hamad Rus, home of the Kashites who once lived East of Eden. Their long-time enemies, the Inyosh, the undead Children of Lilith, had driven the Kashites west into Northern Africa millennia earlier. Casting a spell to destroy the Inyosh, the Kashites had instead changed them into formless wraiths that killed to obtain blood for their god, Nergal. Now, the Inyosh have awakened, and Rome is at risk.