It was supposed to be an ordinary day at the pool, but when lifeguard Nick hesitates during a rescue, seventeen-year-old December uses her gift of foreknowledge to save the drowning man instead. The action comes at a cost. Not only will Nick and December fall in love, but she also sees thathis life is now at risk. The other problem? They're basically strangers. December embarks on a mission to save Nick's life and to experience what it feels like to fall in love—something she'd formerly known she'd never do. Nick, battling the shame of screwing up the rescue, resolves to make up for his inaction by searching for December's mother, who went missing nine years ago. As December and Nick grow closer, her gift starts playing tricks on her and Nick's family gets closer to an ugly truth about him. They must both learn what it really means to be a hero—before time runs out.