One morning, someone fell from a building and died on a truck. The investigating detective Borden (Chris Messina) arrived at the scene and found that the first scene was not where the truck was parked, but in a building not far away. At the same time, an elevator in the building suddenly broke down and hovered near the 20th floor, trapping three men and two women in the elevator. The maintenance personnel sent by the building security also failed to solve the problem. In the closed elevator, the five people were anxious and quarreled because they were trapped. At this moment, the lights in the elevator suddenly went out for more than ten seconds. After a short period of darkness, one of the girls was injured and bleeding on the back. The security decided to call the police. After receiving the report from the building security, Borden rushed to the monitoring room. When he was about to mobilize the police to rescue the trapped people, the lights in the elevator went out again. After the lights came on, people found that one of the men had been killed, and the murderer seemed to be only one of the remaining four people...