Caleb Durant is half demon. His mother has spent his entire life telling him that he's the Antichrist, destined for great and evil things. He's mostly just trying to pass calculus. After his school principal's fatal and not-entirely-unintentional accident, he's forced to moved to a small country town, but he hopes he can at least get some solitude. But Andras, his demonic guardian, has made a friendly wager with an angel, and Caleb's soul is the prize. Isaac Mitchell, the sheltered Southern Baptist tasked by an Angel of the Lord to turn Caleb toward the light, is determined to keep his new friend on the straight and narrow. Isaac himself, however, is having some trouble remembering to keep his task and his feelings separate.