One ordinary late night, Su Yuan, a 28-year-old office worker, received a text message from an unknown number. The content contained only three words: "Don't open the door." What the sender showed was actually his own mobile phone number ten years later. At first he thought it was a prank, until there was a regular knock on the door, which completely coincided with a horrible night in his memory that had long been blurred. This text message started an inescapable cycle. He must find the key to breaking the situation in countless "tonights", otherwise he will always be trapped in the life-and-death decision of opening the door or not.
