Hong Kong teacher Kang Sengui is said to be a "happy ghost" with strong mana in his previous life. With the help of the "Happy Ghost", he gains superpowers beyond ordinary people. The principal's daughter, Anne, is Kang Sengui's girlfriend, and the two are very affectionate.
One day, four naughty students in Consengui's class are stranded into the wilderness because of mischief. They accidentally picked up a set of armor from an ancient general and brought it back to the dormitory. The soul of this ancient general became a essence because of absorbing the yang energy of the four people. When he saw the photo of the four students and Kang Sengui with his girlfriend, the memories of his past life came back to his mind. It turns out that Anne killed the general in her previous life, and the general's spirit is determined to take revenge in this life!
At this time, the "happy ghost" was preparing to go to the West Heaven to become a Buddha and temporarily leave Kang Sengui for a while. Unfortunately, this was the time when the general was preparing for revenge. The general, who had turned into a demon, began to do evil, sucking the yang energy of the two policemen dry and regaining his vitality. Then he began to prepare for revenge. The four boys suddenly came to their senses, saved the scene in time, and fought the evil spirits. The demon inadvertently burned the feathers, and as a result, summoned the "happy ghost" back.
The demon summoned the tiger in the painting and attacked the crowd. But "Happy Ghost" subdued the Tigers. Seeing this, the evil ghost summoned Wu Song again. The "happy ghost" threw Kang Sengui at Wu Song in time. After a fierce battle, the crowd finally eliminated the evil spirit.
The film no longer features a beautiful girl as the main character, but four boys as an auxiliary to the plot.