The next evening after young architect Ray (Alex Fong) moved into his new home with his wife May (Shu Qi) and 5-year-old son Zilu (Tan Junhao), something strange happened. When May was playing with Zilu in the rooftop garden, she saw Zilu being pulled out of the rooftop by a powerful force and falling off the building. Then, May heard the child crying for his mother. What's more terrifying is that all of Zilu's toys and clothes disappeared. With the help of the police, Ray and May knew that the director knew all this because of the mysterious "monster" (Lin Jiaxin) hiding behind them. In the process of fighting with the "monster" for their son, Ray and May gradually realized that the mysterious "monster" was hiding an unknown sad story under its ugly and terrifying appearance.