On the eve of the senior class lake retreat, seventeen-year-old ice queen Iris Strasser watches her future collapse before her eyes—literally—when she crawls out of a malfunctioning time machine, mumbles a cryptic warning, and then falls dead. Sudden cardiac arrest. Cancelling the retreat is a no-brainer, but her infuriating arch nemesis—popular prick Cory Holland—will have none of it. Still raw from using time travel to save his ungrateful crush, he’s been looking forward to a weekend of zip-lining, bonfires, and hot bikini-clad girls getting frisky in the lake all summer—Iris Strasser notwithstanding. Besides, if anything goes wrong, they can always use the time machine again. But when the retreat unfolds in a series of bizarre and deadly accidents, each preceded by a ghostly figure rumored to be death itself—here to finish the job Cory and Iris short-circuited the last time around—they realize they’re not the only ones dipping their fingers into the past, and now the ripple effects are catching up with them. Now there’s only one way for Iris to outsmart death: she must set aside her hatred of Cory and learn to trust him completely—even if it means letting him get dangerously close to her when she’s most vulnerable. Cory, for his part, never anticipated that he would want to. This time, though, meddling with the past has larger consequences than either of them could have imagined.