Llana of Gathol

Llana of Gathol was published in 1948 as a collection of four interconnected novellas that Burroughs had written for Amazing Stories magazine in 1941. The protagonist is Llana of Gathol, John Carter's granddaughter, who has grown up enough to drive her own subplots by this point in the timeline. Each of the four novellas takes Carter and Llana into a previously unexplored corner of Barsoom.

The first novella, The City of Mummies, takes them to the lost city of Horz and an ancient settlement of orovars, the original yellow-haired Martians whose race had been thought extinct. The second, Black Pirates of Barsoom, features Carter rescuing Llana from First Born raiders. The third, Yellow Men of Mars, takes them into the northern polar regions. The fourth, Invisible Men of Mars, involves another lost civilization with new technology. The episodic structure makes the book lighter than the novel-length entries, but the worldbuilding extensions are genuinely valuable. A late-career return to form.