The film is set in 1999, a shooting incident at Columbine Middle School in the United States that shocked the world. It tells the story of a vicious shooting incident in an ordinary middle school in the United States and what happened a few hours ago. John failed to play truant and was forced to go back to school by his father. Arya likes photography. He took some photos of people and scenery inside and outside the campus and went back to school to develop them himself. Mi Xueer was left out in the cold and depressed. He went to the school library to help with his homework. Jordan has just made a new girlfriend, Kelly, who has been talked about by Nicole and other girls. At this time, Eric and Alex, who are often bullied by others, inadvertently bought guns through the Internet. After taking a nap at home, they decided to kill people on campus. After simple planning, they walked into the teaching building in American military field uniforms, and the fate of the children changed. The tragedy happened on this cloudy afternoon.