Rhea Harmon is a living target for the Devil as she possesses the power to detect one's deadliest sin at first glance. Intended to be used as a weapon of war, the Devil sends Paimon, his right-hand man and top collector, to claim her soul and bring her to him in Hell.

But the Devil isn't the only one who is interested in Rhea.

When Paimon arrives to collect her soul, he's immediately taken with her and the resemblance she bears to his late-wife, Marissa. He falls in love with the mortal girl whose soul he is supposed to claim, and instead vows to protect her, thereby severing his allegiance to the Devil and sealing his fate as a traitor.

Consumed by rage and fear, Paimon and Arazel, the Devil's blood slave and ring leader to the circle of Lust, flee Hell in an attempt to save Rhea, but are instead forced to confront their pasts and their presents as they reevaluate the definition of sin and punishment. So what happens when a demon has to confront his demons, when Paimon has to turn to something darker, something more sinister for help?

After centuries of living in exile, banned from their home and their right to rule, The Seven, the keepers of the deadly sins, are only too happy to answer his call, and if Paimon thought it was dangerous to make a deal with the Devil, then he had no idea what it meant to be blessed by the creators of sin.