In Korean funerary tradition, when a person dies, their soul must cross a river called Samdocheon within three days to reach the afterlife. They are not alone on this journey, wooden spirit guides known as Kkokdu accompany them to ensure that death is not a lonely passage. Haesol follows the story of a timid young boy training to become a Kkokdu. One day, he is unexpectedly assigned to guide a soul who has lost both her name and her memory.