This second book in Burrough's Mars series begins with John Carter, now on Earth for the past ten years, pining for Mars from his cottage on the Hudson River. He's transported there just as mysteriously and finds himself in a strange area. He's by an open blue sea, surrounded by plants and animals he'd never seen on Mars. He encounters a green Martian battling for his life against these strange plant-men and this turns out to be his friend, Tars Tarkas. Tarkas fills him in on what's been happening on Mars--how Carter has saved all of Barsoom by opening the oxygen plant years ago--but that his body was never found. Dejah Thoris had offered a reward, for years, until everyone came to the conclusion that he made his way down the River Iss, to the Valley Dor, which is where they are. You see, Martians are extremely long-lived and at age a thousand years make this journey to what they believe is a heavenly afterlife. In truth, what awaits them is death by the blood-sucking plant men and the white apes that feed on the leftover bones. Tarkas had made this journey--not only to find John Carter, but to be with his long-dead love, the mother of Sola. Now they know the truth. And then there are the Therns, pale skinned and hairless, who maintain this secret. They also feed on the flesh of the Martians.They do escape, with the help of a Red Skinned Martian named Thuvia, who has a way with the lion-like Banths the Therns use for guards.
This book also introduces the Black Pirates of Mars. These are the "First Born" and it's rumored they live on one of the Martian moons, periodically making raids to the planet below. In truth, they live below the ground. They prey upon the Therns, as they have for thousands of years and their leader, a horrid old cannibalistic woman, is worshipped as a god. Carter makes a friend among these people and unveils that this old woman is anything but a deity. The most important, revelation, however, is that John Carter has a son by Dejah Thoris and he's someone he meets during this long journey back to the city of Helium.
I found this as entertaining as the first book, with plenty of lost civilizations, weird animals and some unexpected twists.