Urban office worker Lin Xiaoman is trapped in the exact same Monday. No matter how she tries to change her actions or avoid accidents, she cannot stop time from resetting. Just as she is about to be crushed by the endless loop, a series of mysterious text messages guide her to complete various acts of redemption, with skeptical attempts and the help of friends. Lin Xiaoman grabs the key to the prison of time, but as she keeps exploring, she realizes that behind this endless loop lies a meticulously arranged huge secret.