Hong Yoon is on the brink of death after a sudden motorcycle accident when he comes face to face with Lee Taeshin, a grim reaper from the underworld. Yoon pleads desperately for his life, but Taeshin responds with cold indifference—until he realizes that Yoon is the one person he once helped out of genuine compassion in a past encounter. Bound by that rare act of grace, Taeshin reluctantly postpones Yoon’s death. To justify this decision, Taeshin appoints Yoon as his temporary assistant. But the role comes with a heavy price: Yoon must regularly transfer yang energy to Taeshin through intimate physical contact. Though hesitant, Yoon agrees, knowing it's the only way to survive. As the line between duty and desire blurs, both man and reaper are forced to confront their past, their bond, and the strange pull growing between them in the space between life and death.