A killer comet speeds for Earth, big enough to wipe out all life and choke the atmosphere for a century. When the news breaks, soft-spoken freshman Charlotte Hartland gets caught in a flood of panicked students on her college campus - until a black SUV swoops in to extract her. Charlotte's powerful grandfather has saved her a cryosleep berth at the Bunker Reservation Project, a hastily formed effort to save humanity from extinction. When the idealist program begins to unravel, Charlotte will have to fight for her place in the future. But the only person who can help her is a hot-headed construction worker with a grudge against her family - and the clock is counting down to disaster.