As much as I loved A Princess of Mars, its sequel is an even better adventure. It seems less segmented than its predecessor and follows an exciting trajectory that includes everything you'd expect from the originator of the sword & planet genre. As a player of Pathfinder, Dungeons & Dragons, and other RPGs, I loved seeing the dark-skinned, subterranean matriarchal society, as it seemed an obvious inspiration for the now iconic drow. The only down-side to this book is that it ends on an annoying cliffhanger that doesn't adequately pay off the building tension as the plot draws to its climax. Clearly, Burroughs wanted to make people buy his subsequent book (which, of course, I have already done and will read soon), but it makes what would otherwise be a near perfect adventure lack the ability to stand on its own as a standalone book.