After 10 years on Earth, Carter has returned to Mars, only to find himself in Barsoom's equivalent of the Elysian Fields. Technology is so advanced on Mars that the average lifespan is functionally infinite, save for the religious custom of making the one-way pilgrimage down the river Iss to the forested, edenic bosom of the goddess Issus. Martians are obligated to take this pilgrimage upon their 1000th birthday or when the mood strikes them, whichever comes first. None return, except for one in the distant past who spoke blasphemies and was duly executed.
Nevertheless, the heretic was correct. The land of expected unending glories was, in reality, the habitat of carnivorous plant-men and white apes whose mangled victims became the cuisine for the race of white Martians. This is not the true end of the line, however. These white Martians undertake their own pilgrimage to the city of Issus, whereupon they receive a nasty surprise of their own. Carter is dropped into this situation, forced to fight his way through unflinching horror with the prospect of death by Inquisition waiting for him if he makes it out alive.
Thankfully the first person he meets in his valley of death is Tars Tarkas, his Good Indian. He chose to take the pilgrimage in the first of the total happenstances that drive the story along. Burroughs has pulled out all the stops and done away with any vestige of shame. Every plot convenience is employed to thrust us into the next scene. Every person that Carter needs to see him along, from Tars Tarkas to Sola the green Martian to his red Martian bride Dejah Thoris to their son Carthoris, is just where they need to be by fruitful accident.
By employing such tactics, Burroughs ends up undermining his first attempt at a novel with philosophical depth. Indeed, literal cannibalism is used as a metaphor for how religious elites exploit their disciples... Yet I'm consumed by the fact that it's taking the characters several chapters to figure out that Carter has incidentally encountered his own son when I figured it out from the first paragraph in which they shared space. If I try to power through the distraction, well, a metaphor of literal cannibalism is really about all there is.
Worse yet, it is not only the philosophy of the novel but the narrative itself that suffers for Burroughs' easy ways out. When A Princess of Mars was published, Burroughs feared using his own name because it was so far out there. Compared to Gods of Mars, even that work of escapism is a study in restraint. Freed up by his fame with that and Tarzan of the Apes, Burroughs has cranked the Pulpiness to 11. Though intended to speed the action along without convolutions of sense or logic, these plot devices are distractions that bring attention to themselves.