交换:年轻夫妇

　　Mini Mo（郑秀文饰）遭受失恋的打击后，饮食失去控制后体重升至260磅，窈窕身材不再。她与初恋情人黑川约定在十年后的日本相见，但旧貌不再的她深感自卑。偶然相识了跟她同样体型极胖的肥佬（刘德华饰），肥佬非常同情她，决定要帮她重塑魔鬼身材。肥佬以地狱式减肥方法锻炼Mini，为了让她减肥成功，得到更多的金钱让她上专业美容院减肥，肥佬不惜在街头被拳击换取酬劳。令Mini感动不已。　　Mini恢复原貌前去赴约，黑川向她提出求婚，可是她心中仍念念不忘为她默默付出的肥佬，盼望跟他重逢的一天。

Four friends wanted to get away from it all for a birthday celebration in a remote country house, but when a mysterious injured man turns up on their doorstep telling tales of a city ravaged by a mysterious epidemic and the looters who have pursued him, the friends rally to help. As the night progresses, it becomes clear that all is not as it seems, plunging the friends into a battle for survival that challenges their deepest fears.

 这部1973年的小说由安部公房创作，讲述了一位无名男子放弃自己的身份，头顶一个大纸箱生活的故事。在东京街头游荡时，他遇到了各种各样的人物。