Haruki is traveling to the vast plains of Hokkaido, Japan, on a lone bus about to enter a three-kilometer-long tunnel. He is grieving for the loss of his wife when the tunnel collapses and traps the bus inside. In the darkness that follows, he manages to fumble out of the bus with the only other survivor, an astute and gentle woman who reminds him of his late wife. Without any light to guide them and with only each other to depend on, they try to escape the stifling darkness and along the way find themselves confronted by their pasts and given their last chance at intimacy, and ultimately, absolution.

A realist story that plays with surreal elements, the tale poses a simple question: what is the meaning of hope?