The red planet is no more. Now green and verdant, covered by seas and settlements, Mars has been dramatically terraformed from a desert world into one where humans can flourish. All that remains is to finish creating a breathable atmosphere and an ecosystem full of wondrous genetically engineered Martian creatures.

But as Mars reaches its final transformation, Earth is in peril. The Great Flood threatens an already overpopulated and polluted planet, and Mars faces a population explosion or interplanetary war. Now the First Hundred settlers of Mars, having attained near immortality through longevity drugs, are pulled into a fierce new struggle.

Ann, the head of the Reds, a group devoted to preserving Mars in desert state, again takes on her old nemesis Sax Russell, who is an architect of the "green" terraformers - and the consequences of their bitter battle will be an ice age that threatens to turn Mars into a frozen wasteland.

As courageous men and women of new generations join the first Martians, the human drama at the center of this breathtaking epic explodes in political upheaval, leading to new explorations into the solar system and to choices that will decide the ultimate fate of Mother Earth.