He never expected to find a demon playing Goldilocks in his bed.
Demons were evil, cruel, and hated by everyone in the Arcane, so when Wade found a demon not just his house house, but sleeping his bed, his first instinct was to attack. Except this demoness was fierce and stronger than him, easily matching him. But rather than killing him, she delivered a grave warning; something much, much worse was coming.
Instead of ending her, he's forced to work side-by-side with her. If she is to be believed, they only have until the next full moon to find a way of saving the world from a demon worse than any he's ever heard of.
But he can't trust her, and even if she's right, stopping the demon lord won't be easy. They don't know exactly when or where he'll arrive, and every time they turn around, they're being attacked by his minions. While he has to admit the demoness is vicious in a fight, it will only take one wrong move to end them and doom the world.