Bradley had been captured by the ghost-like creature, which is soon revealed to be a naturally winged human being, belonging to a subgroup of humanity known as the Wieroo. The Wieroo takes Bradley to the island of Oo-oh, set in Caspak's inland sea. It attempts to keep Bradley in a prison, but he escapes through a secret passage. He meets Co-Tan, a member of the highest human race of mainland Caspak, the Galu, fully human and of a neolithic cultural level. They enter the chamber of the Wieroo king, a huge member of the race, and Bradley kills the creature with its own sword.
Co-Tan and Bradley escape the city of the Wieroo and live for several months on the forested coast of Oo-oh. Finally, though, they are discovered by Wieroo. They succeed in capturing two of the Wieroo and forcing them to fly to the mainland, one bearing each of the humans.