In an old residential building, seven people saw the same murder scene through the windows. The deceased was Yu Deshui, the leader of loan sharks. He died on the sofa at his home with a knife stuck in his chest.
A male body was found in the elevator of the landmark building "Times Building" in Dongze City. The deceased was Zhou Muzhi, a well-known entrepreneur. He was stabbed seven times and died tragically.
Strangely, the elevator monitoring showed that at 17:23 that afternoon, Zhou Muzhi entered the elevator alone and pressed the 13th floor button. The elevator door closed, and at 17:24 the elevator reached the 13th floor. The door opened - Zhou Muzhi had fallen into a pool of blood.
Just one minute. The elevator never stopped and no one else entered or exited. This is a perfect secret room.
Interpol Chen Xiao took over the case. He called up the surveillance of the entire building and found that a total of thirteen people took the elevator up and down in the five minutes before and after Zhou Muzhi entered the elevator. Chen Xiao found these thirteen people one by one and asked them to recall what happened in the elevator that minute.
Thirteen testimonies pointed to the same conclusion: Zhou Mu was the only one in the elevator.
However, forensic identification showed that the seven stab wounds on Zhou Muzhi's body came from at least three different directions, and it was impossible to commit suicide. The murderer is in the elevator - the murderer is one of these thirteen people, and the other twelve people are all lying.
Chen Xiao must pry out the hidden truth from these thirteen mouths. As he gets closer to the answer, he discovers that the thirteen men share a secret - they are all related to an unsolved cold case from five years ago.
