It's New Year's Eve 1999, and everyone over twenty has perished. It's a teenager's dream come true-no adults, no rules, no one in charge-until the kids realize that as they and those they care about turn twenty, they too will disappear. So instead of a 24-hour-a-day party, the teenagers begin a desperate struggle to save their own lives, and the future of humanity. The key is nineteen-year-old Julia, who possesses a secret knowledge of how to save civilization - but the clock is ticking, for Julia turns twenty on New Year's Eve 2000, at the turn of the millennium.