The Ark. A space habitat. Where thousands and thousands of people live in space. Ninety-seven years after a devastating nuclear apocalypse wipes out most human life on Earth, thousands of people now live in a space station orbiting Earth, which they call the Ark. Three generations have been born in space, but when life-support systems on the Ark begin to fail, one hundred juvenile are sent to Earth in a last attempt to determine whether it is habitable, or at least save resources for the remaining residents of the Ark.