At a school where Quantum Paradox 101 is a required course and history field trips are literal, sixteen year-old time traveler Bree Bennis excels...at screwing up.

After Bree botches a solo midterm to the 21st century by accidentally taking a boy hostage (a teensy snafu), she stands to lose her scholarship. But when Bree sneaks back to talk the kid into keeping his yap shut, she doesn't go back far enough. The boy, Finn, now three years older and hot as a solar flare, is convinced he's in love with Bree, or rather, a future version of her that doesn't think he's a complete pain in the arse. To make matters worse, she inadvertently transports him back to the 23rd century with her.

Once home, Bree discovers that a recent rash of accidents at her school are anything but accidental. Someone is attacking time travelers. As Bree and her temporal tagalong uncover seemingly unconnected clues—a broken bracelet, a missing data file, the art heist of the millennium—that lead to the person responsible, she alone has the knowledge to piece the puzzle together. Knowledge only one other person has. Her future self.

But when those closest to her become the next victims, Bree realizes the attacker is willing to do anything to stop her. In the past, present, or future.