Lucky Encounter 1992

A villain Chan, kidnaps his little nephew Bou, but eventually kills the little boy, leaving both his spirit and the ransom in the house. After failing to get the ransom out of the house several times, which is installed with advanced alert system, Chan hires Wong, who used to be a thief king, to make it for him. Wong then dispatches his son Fatty and Wai, both of whom are interested in electronic science and technology, to go to the house, but they are fooled by Bou. They finally knows what happened to Bou and decide to help him out by fighting against Chan. Meanwhile, Chan hires a master who is good at catching ghosts to get Bou. A fierce fight thus goes on.