When Seattle’s most elite private school—alma mater of Bill Gates—becomes the controversial recipient of a prototype quantum supercomputer, senior class prankster and genius computer whizz Cory Holland is determined to hack it . . . that is, if he can find the time between crashing parties and making out with his archenemy’s superhot ex, Samantha. But Cory soon realizes the spooky coffin-sized machine humming away in his school’s basement isn’t a computer at all. Inside the machine, time appears to cycle in endless loops. Food molds in seconds. Cell phones drain in minutes. Most startlingly, it appears possible to step inside at the end of the loop . . . and step out into the past. But when the machine delivers a cryptic warning that Samantha died in a car crash, his memories of her instantly begin to vanish—leaving only lingering moments of déjà vu. Someone’s been screwing with the past. Now he must do the unthinkable: alter the timeloop to save the life of the girl he loves, only to forget everything about her.

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.

Time travel sucks. You have to squeeze inside this fridge-sized quantum computer and suffer hours of mind-numbing boredom while it loops back in time. No light, barely enough air, total solitude. All the time in the world. It’s also like a drug. After her first nine-hour timeloop, teenage loner Iris Strasser craves another loop, if only for the rush. Determined to one up her, pretty boy Cory Holland ignores the warning signs that they’re meddling with something dangerous and programs in his own timeloop, daring Iris to make increasingly reckless trips into the past. But when Iris steps into a timeloop and never steps out, leaving Cory with an empty time machine and an ache in his heart, he must come to grips with the unthinkable truth—he’s lost her inside an infinite loop from which she can’t escape. He’s trapped her in the past, and this time, time travel can’t reach far enough back to save her.