The story of Yeon-Hee who appears to be having a happily married life but is actually experiencing domestic violence. Little by little, Yeon-Hee begins to fall into danger after her SNS account was hacked.
A group of tired commuters have caught the last train home, ready to hop into their beds for the night. However, their train soon veers off-course and crashes into an abandoned tunnel. The three surviving commuters; withdrawn mother Yi Ling, her son Luca