Heo Young-poong drifts through his thirties without ambition, direction, or much connection to anyone—until a serial killer abruptly ends his life. Awakening as a ghost, invisible and unable to touch the world, he expects death to be as pointless as life was. Instead, he begins interfering in the lives of people he once knew: protecting an old love, helping a desperate friend, confronting his grieving family, and eventually searching for the truth behind his own murder. With each strange afterlife mission, the man who believed himself useless discovers purpose for the first time. Darkly funny and unexpectedly moving, the novel transforms a murder mystery into a story about regret, second chances, and learning how to live only after dying.