In "The Devil in Iron," an ancient demon, Khosatral Khel, is awakened on the remote island of Xapur due to the meddling of a greedy fisherman. Upon reawakening, Khel resurrects the ancient fortress which once dominated the island, including its cyclopean walls, gigantic pythons, and long-dead citizens.

Meanwhile, Conan — a leader of the Vilayet kozaks — is tricked by the villainous Jehungir Agha into pursuing the lovely Octavia to the island of Xapur. Jehungir Agha plans for Conan to fall into a prepared trap on the island. The unforeseen resurrection of the island demon and its ancient fortress, however, interrupts these plans.

When Conan arrives on Xapur, he must defeat not only the forces of the Agha led by Jelal Khan, but a giant serpent as well, and the iron-fleshed monstrosity that is Khosatral Khel.