阿燦（廖偉雄飾）與肥則(鄭則士飾)一對活貝警界立下不豐功偉績。但每次都是烏龍百出，錯有錯著之下破案的，一次因涉嫌收藏大陸的非法人蛇，倆人同被革除職務。二人于無意中得悉一名叫契爺的黑社會頭子，擄去一富翁的小孫，但倆人是被革退的警員，又怎樣去處理或能否撲滅契的犯罪集團呢！　　肥則為了娶阿芳（鄭麗芳飾）為妻，收留了從大陸偷渡過來的大姨媽及其女阿珍（阮佩玲飾）。阿燦愛上了賢淑可愛的阿珍，兩人很快墮入愛河。另一方面，犯罪集團主腦契爺（羅烈飾）及得力女助手阿JOE策劃一樁勒索案，但取贖金時險比警方捉拿。無計可施時，契爺捉走阿珍及阿芳來威脅阿燦及肥則替他們取贖金，并在他們身上裝了一遙控計時炸彈…

　　The nightmare was about a demonic possession. A long time ago, there was an evil in a small town and it was jealous of the girl and would never let her go, since the devil loved the girl. One night, the evil raped the girl and she became pregnant. After months the girl could not hide her baby, her father figured her secret out and clapped the girl in irons and locked her room door. But the evil put the gun to her father' temple and saved the girl. The father had a stroke and had been sleeping on the bed for three months and died. Time went on and the girl brought a child into the world. Naturally, people who were living in the village heard the story and they did not want to see neither the girl nor the baby since when the baby was born, plants dried in the field, fishes lost in the lake and people had prayed to the god for rain, but nothing changed in the village. People got so angry, dug a hole in front of the fountain, put her into the hole and threw stones at her face. The girl died soon after. The evil went off the deep end, took a revenge of the village and killed everyone except two sisters because the evil wanted them to take care of its baby...

　　克萊爾小時候有個假想的朋友，長大后她回到童年的家，卻遭到“曾經朋友”的折磨。盡管是一部美式恐怖片，風格卻非常多元化，從預告可窺緊繃于弦的氣氛。

　　一位悲痛欲絕的年輕女子必須面對她內心深處的恐懼和一種致命的水生生物，努力證明湖底的恐怖是真實存在的。