After a global catastrophe nearly wipes out humanity on Earth, Earth's elites fled to Kepler-209 space colony. A young astronaut named Blake from the Kepler colony returns to Earth with fellow astronauts Tucker and Holden. Their mission is to test whether Earth is suitable for human habitation and reproduction. Kepler-209 residents have modern technology and space travel but they have become infertile from heavy radiation there. This is the second attempt to return to Earth.The space capsule lands roughly on a tidal flat near a weather beacon that broadcasts telemetry data back to Kepler-209. Holden is killed, while Tucker commits suicide after a band of fertile humans, nicknamed "The Muds", wounds him and captures him and Blake, and removes technology from the shuttle. Blake is imprisoned by the Muds and nearly drowns, but she is saved by a girl named Maila.The Muds are invaded by a hostile group that kidnaps all of them. They are taken to a cargo ship that rises above the frequent floods and storms. The aggressors are led by a former Kepler-209 resident named Gibson, who was a survivor from a previous Earth mission led by Blake's father, once thought to have no survivors as its capsule was destroyed along with its communication equipment.Blake realizes she is fertile, and she meets the children of the Muds, whom Gibson is educating. Gibson claims the Muds killed Blake's father, but Blake learns that he has been locked away because he sided with the Muds, believing that Kepler residents should never return to Earth. After a brief reunion, Blake discovers the girls are being held captive for Gibson's future breeding plans. She sides with the Muds, attacks the guards, and releases the girls and their families.She tries to stop news from Earth being broadcast back to Kepler-209, but Gibson sends the data. Blake strangles and drowns Gibson, almost drowning herself, but Malia's mother rescues her and revives her. Blake and her father rejoin the Muds and they set out in a tugboat. A closing scene shows a habitation on the tide flats and a group of children playing. (copied from Wikipedia)