In a world where humans and monsters coexist, Ji-Hwan, a young man with the rare ability to see and interact with the spirit world, is a "Night Stalker." These individuals are feared and ostracized by society, forced to live in the shadows and survive by their wits. Ji-Hwan's life takes a drastic turn when he befriends a mysterious woman named Soo-Jin, who possesses a rare and powerful healing ability. As they work together, Ji-Hwan's existence is threatened by a series of mysterious events and a powerful organization that seeks to exploit his abilities for their own gain.