Lee Jeongyeon lost everything the day his lover died saving a stranger. A stranger none other than, Ki Seohyeok, the boy Jeongyeon once taught. Drowning in grief and haunted by the unfairness of his loss, Jeongyeon seeks out the Seohyeok, driven by a desperate need to see the life that was bought with his lover's blood. But as Seohyeok begins to fill the empty spaces in Jeongyeon's life, the mourning teacher realizes that some debts are paid in ways more dangerous than death.