A lone vampire bat sneaks through the mirror portal and ends up in the human world. Instead of apples, it now craves something far richer. And unfortunately for Jeongguk, he's its next snack. Jeongguk can't remember any of his activities past sundown. The light hurts not just his eyes, but burns his skin. And he's thirsty. So very thirsty. It's up to BTS to save Jeongguk from himself before he drinks the whole city dry. Too bad Park Jimin is his primary target.