Chun Yu is a university student whose life is thrown into unspeakable turmoil when she receives a chilling text message that reads: “I know what the 19th floor of hell is.” Soon, she realizes that other students on campus have received the very same message. Before long, she learns that she has been sucked into the macabre reality of a mobile game that takes place in a ghostly “haunted” building where every floor is full of dangers, horrors, and terrifying secrets. Worse still, she observes, when unwitting players fail to beat a level in the game, they immediately fall into a coma. With no other choice, she begins to play the game, where she meets fellow player Gao Xuan. The duo begins to navigate the perils of the building together, slowly heading toward the dreaded 19th floor. But what awaits them if they make it to the game’s final, decisive level?