龍雁飛（許冠文 飾）是一個著名的武俠小說家，十年了都沒有新的作品面世了，不過以往的暢銷作品仍然帶給他客觀的收入，生活無憂。他的女兒Sophia（楊千嬅 飾）是個早已到了適婚年齡，但她戀愛運甚差，只想找一個真正可以過日子的人結婚，其實她一直暗戀自己的上司——花花公子Frankie（劉青云 飾）。Frankie因為意外要搬到Sophia的家住，龍雁飛看見自己心愛的女兒被Frankie當工人使喚，心里很不是滋味，便對Frankie充滿了敵意，但在后來的相處中，兩個男人又成了知己……

本片改編自同名小說，故事始于高一夏天，坂平陸（高橋海人 飾）與水村真奈美（芳根京子 飾）在泳池事故后靈魂互換。兩人堅信能恢復原狀，苦尋方法，然而15年過去，依舊未能換回。升學、初戀、就業、結婚、生子，他們只能以彼此的身體走完人生重大節點。直到30歲那年夏天，真奈美突然說：“我或許知道怎么換回來了。”命運的齒輪，開始再次轉動——

　　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...

　　邁可透過一張光碟，參加了一場刺激的游戲，在月黑風高的晚上他發現自已稍稍走進一間屋子并從廚房拿刀子殺死一個沈睡著的男人當邁可醒來時他興奮極了，這一生他從沒有這么刺激和開心過，第二天當他看到新聞。天?。∧羌\殺案真的發生了嗎？后來第二張CD又寄來了，他決定結束這場荒謬的游戲，但主謀者從邁可的電腦中走出來，他竟是一具有形象的＂人＂，并且一再要脅邁可再玩下去，也挑唆他面對恐懼和幻象，邁可就像受催眠一般他無處可逃，主謀者已經完全控制了他使他分不清什么是真什么是假……