The Bishop twins Artemis and Magnus are hunters of the supernatural and their hunt has brought them to Kenai, Alaska, in search of a hellhound that spooks the locals. While there, they get a room at the Donahue family's inn that the hellhound seems to guard and meet the unusual Caleb Donahue, a teenager that the whole town—and perhaps even members of his own family—seems to hate. Though they came to kill a hellhound, the twins might just end up saving it instead.
When Hell Freezes Over contains examples of:
- Badass Bookworm: Magnus is incredibly well-read and more bookish than battle oriented, but can still fight when he needs to
- Happily Married: Caleb's parents, again, and at first, Magnus and Artemis' parents
- Hellhound: All Hellhounds are Hunter-types since the Guardian and Portent types are actually different dogs. Church Grims are Guardians and Black Dogs are Portents.
- Hunter of Monsters: Magnus and Artemis Bishop have been raised by their mother to hunt all supernatural creatures
- Mama Bear: Do not threaten Caleb when you're near Grace if you want to live
- Missing Mom: The twins have no idea where their mother is, but they don't seem very concerned since they know she can take care of herself
- Papa Wolf: Do not threaten Caleb around Daniel
- Slave Race: Hellhounds are said to be this to demons
- Star-Crossed Lovers: Magnus falls in love with Caleb
- That Thing Is Not My Child!: Caleb's mother has felt like this ever since he was born
