Jeong-won (played by Park Shin-yang) is an interior designer who is going to marry his fiancée soon. Once, he overslept on the metro and found two girls sitting side by side beside him after waking up at the final station. He left without waking them up. The next day, Jeong-won saw it in the news that those two girls from yesterday died in the train and he was very guilty. One day, he met Yeon (played by Jun Ji-hyun), a girl who has hypersomnia. After waking up from a coma, Yeon discovered that she got astral vision and could see all the ghosts. Jeong-won found his rescue and hoped Yeon could help him figure out the ghosts of the two girls....