They Went to the Forest in the West is a story about people who walked into a labyrinth symbolized by a forest. One day, Yi Gyeong-in, a forest manager, disappears into the forest and his younger brother Yi Ha-in, who is a lawyer, begins to search for him. As he follows Gyeong-in’s steps, he discovers that his brother’s successor, villagers, and all the employees at the forestry research center deny Gyeong-in’s existence completely. However, by doing so, they end up exposing a secret that exists between them.

Around this time, Yi Ha-in dies of a hit and run accident. While part one consists mainly of the search for the missing brother, part two and three show how the search is postponed indefinitely. This is because the truth of the event is wrapped in mystery and circumstances take place where the characters cannot be sure of their actions.

The person at the center of this uncertainty is Yi Gyeong-in’s successor and the main character of the novel, Park In-su. He is an alcoholic who has been cast out by society and an incompetent father cut off by his family. As his addiction gets worse working at the forest and as he begins to hear things, his family loses faith in him and leaves him. In-su trembles in fear because of the unknown noise that seems to come from the forest. The secret of the forest seems to be unveiled when it is revealed that Mr. Jin at the research center and his retired friends have been carrying out large-scale illegal lumbering.

However, one secret leads to a bigger secret, with the forest sealing the secret at the end.