[2][3] The story details Quatermain's past life regression to a Stone Age ancestor and the various adventures involved.

Lady Ragnall herself informs Allan that she has used the taduki once more and discovered that their ancient counterparts, Amada and Shabaka, were indeed married.

Six weeks or so later, Allan has a psychic experience and later learns that Lady Ragnall had died of heart failure at that moment at the site of her husband’s grave in the Temple of Isis.

He is tempted to break his vow and use it, but finally resolves not to when his friend, Captain John Good, calls on him.

Wi challenges and kills his corrupt chief Henga and institutes reforms in the tribe: monogamy, decision by council, and the use of new technology.

They determine that Good was Moananga, Laleela was Luna Ragnall, and Allan’s sometime companion Hans was the outcast Pag.

Allan surmises that they are not actually experiencing past lives, but that the taduki drug has “the power of awakening the ancestral memory which has come down to us with our spark of life through scores of intervening forefathers.” He also guesses that Wi and his companions dwelt in Ice Age Scotland, 500,000 or 50,000 years ago, and that Laleela came from southern Ireland or northern France.

[8] Philip José Farmer and Christopher Paul Carey used characters and plot elements from Allan and the Ice-Gods in their Khokarsa series of prehistoric adventure novels, a body of fiction which in Farmer's words "represents an amalgamation between [the works of] Burroughs and Haggard.