While driving through the kilometer 31 of a lonely road, Agata Hameran hits a boy. She leaves her car to help the victim and another car runs over her and she falls in a deep coma. Her twin sister Catalina telepathically feels the pain of Agata and hears her whispering for help. Together with her boyfriend Nuno and Agata's mate Omar, they return to the km 31 of the road, and find out that the place is surrounded by supernatural accidents caused by the ghost of a mother that lost her boy many years ago. Further, Catalina discloses that the spirit of Agata is trapped between the worlds of the living and the dead.
KM 31: Kilómetro 31
Following a horrible car accident on a wooded road near Mexico City, Agata goes into a coma. Her twin sister Catalina must try to solve the mystery of her sister's accident next to the Km. 31 marker and discovers a terrifying local legend.