While on a subway, a man (dubbed the Lost Man) witnesses another man scolding a mother for failing to calm her crying baby. The Lost Man then receives a call from his ex-girlfriend, informing him that she is pregnant with his child and asking him what to do. He loses connection while trying to exit the station, and finds himself in a deserted, endlessly looping corridor. Reading a set of instructions, the Lost Man learns that he needs to reach Exit8 by turning back whenever the corridor has an anomaly and moving forward when there is none. Anomalies can range from faces on posters tracking his movements, to blood raining from the ceiling. Any mistake returns him to Exit 0, resetting his progress. Upon reaching Exit 5, the Lost Man receives a call from his ex, who continues to implore him to help her reach a decision. He relays the altercation on the train that he had witnessed, recounting that nobody defended the woman. He tearfully confesses that his failure to stand up for the woman makes him feel unfit to be a father. His ex then appears in the corridor, revealing her to be a mere apparition and thus sending him back to Exit 0. Eventually, the Lost Man meets theBoy, a small child who had been following the Walking Man, an unresponsive entity theLost Man sees walking down the corridor in every loop. The Walking Man used to be similarly lost, but became part of the loop after abandoning the Boy for a false Exit8. Although initially mute, the Boy proves highly perceptive, and with his help, the Lost Man makes steady progress. The Boy gradually opens up to him, confessing that he ran away from his mother, and gives him a
hermit crab shell for good luck. Upon reaching Exit6, the corridor is suddenly flooded. After having a vision of himself, his ex, and their son—revealed to be the Boy—at a beach, the Lost Man tries to save theBoy, holding him above the water and comforting him before he himself is swept away. After regaining consciousness, the Boy turns the corner to Exit8. TheLost Man appears a short while later; initially doubtful on whether it is the real Exit8, he sprints toward it upon remembering the Boy's shell. This returns him to the real world, where he calls his ex, promising to meet her at the hospital. He enters the same crowded train he had taken earlier and once again witnesses the man berating the mother and her crying child. However, this time, the Lost Man turns to berate the man.
Cut scene Kawamura wrote in the novelization of the movie that he cut a scene before screening it at Cannes, because he thought that it was too scary to show. Among the parts of the scene that were cut (and reserved for a possible future "director's cut" version) are the backstory of "the Walking Man"; how "the Lost Man" could become a "Walking Man"; the reason for the photobooth and the pile of discarded items; a "Homeless Man". According to Polygon, who conducted an interview with Kawamura, the scene involves "the Lost Man" looking at the images from the photos in the dispenser, with the subject's face getting distorted after each set of photos dropped. The subject was him becoming a "Walking Man". Kawamura felt that making "the Lost Man" face the dreary reality of his repetitive, boring life was just as terrifying as facing supernatural terrors. ==Symbolism==