War-Gods of the deep: The adventure begins when the widowed ruler of a sub-oceanic kingdom spies a woman on the land who closely resembles his late wife. Believing that she is the reincarnation of his beloved spouse, the mer-king orders his gill men to kidnap her. At the earth's core: When the experiment of a scientist and professor goes awry, their "iron core" leads them to the underground kingdom of Pellucidar, where the Wing People are ruled by the monstrous, flying Mahars. With the help of the professor, Innes leads the Wing People in revolt against their evil masters.