Set 97 years after a nuclear war destroyed the Earth, the last humans live in space stations which have banded together to create the "Ark". In the "Ark" every crime no matter the reason for it or it's severity is punishable by death. ("Floating") But the "Ark's" life support is failing and 100 teens who committed "crimes" are declared expendable, and are sent to Earth to find out if it is habitable. They are sent with wristbands that monitor their health and send it to the "Ark". The 100 quickly develop a "no law" rule on Earth, but while in search for food the teens discovered they are not alone. There are other humans on Earth, as well as mutated animals.