Lin Mo, the administrative specialist of Shengjing Office Building, is one of the last people to leave work in this cold building. When she got used to the problem of the old No. 3 Elevator being often stuck, a nightmare came quietly - on the elevator screen at midnight, a scarlet "404" replaced the familiar floor. After the door opened, there was a dilapidated corridor filled with an outdated atmosphere, and on the wall were faded posters with the date stuck in 2020.
No one believed what she was going through, and the surveillance was always "normal," as if the all-devouring 404th floor was just an illusion of her being overtired. But the anonymous warning note, the old key that mysteriously appeared in the workstation, and the face on the poster in the corridor that was exactly the same as the protagonist of the mysterious disappearance three years ago, all forced her to admit: this is definitely not a malfunction.
As the investigation deepens, the truth about the disappearance, the shady story of the company's top executives, and even her own childhood memories deliberately sealed away by her mother are all intertwined with the strange legend of this building. Lin Mo realized that Elevator 404 was not only the entrance to an alien space, but also a cage of obsessions where the souls of the dead were still alive. She must uncover the hidden evil, otherwise the next time the elevator door opens, she will become the new "missing person"...
