Chen Mo, an ordinary programmer, woke up after working overtime and was trapped in a strange classroom full of mold. There is no exit here, only a back door that opens regularly. Every time you open the door, you will see a terrifying copy of an uncertain life or death - the Stitch Monster in the midnight ward, the cursed clown in the abandoned amusement park, the life-seeking female ghost in the haunted school... The copy is full of dangers, human nature is twisted in desperate situations, and betrayal and cooperation are intertwined. Chen Mo relied on a notebook left by his predecessors and a mysterious silver knife to survive side by side with his new friends Zhao Qiang and Li Na. They not only have to fight against bloodthirsty monsters, but also compete for limited resources and find key fragments scattered in the copy. Every time you pass a level is a fluke, every time you open the door is a gamble. Only by surviving can you have a chance to uncover the secrets of the infinite classroom and find the door to the outside world.
