As a child, Grace was attacked by the wolves living in the woods behind her house and almost killed. Her memory of the event is hazy, but she remembers the yellow eyes of the wolf that saved her, and since then she’s seen him every winter lurking just outside her backyard. In the summer, however, he’s conspicuously absent, and she misses him keenly. Sam, the wolf in question, is a werewolf, and while he watches over Grace as a wolf, as a human he can’t get up the courage to speak to her. When a boy from Grace’s school is killed by wolves, she interrupts the hunting party that forms, but not before wolf Sam is shot and, turned human by the injury, ends up bleeding on her back deck. Once they finally meet, their long-held interest in each other turns to romance, but staying together looks unlikely as Sam’s time as a wolf approaches.
Stiefvater offers a unique take on the werewolf mythology in this supernatural romance. Rather than changing with the full moon, her wolves change with the temperature: they are wolves in cold weather and humans in warm weather. The longer they are werewolves, the less frequently they change back and forth, eventually becoming a wolf for good. The temperature required to change varies, as does the length of time they have before losing their humanity for good, but in general the younger werewolves change with the seasons more often and have more time as humans ahead of them.