《半醉人间》讲述的是发生在一间名为“半人间”的现代酒吧里的故事。影片通过主人公阿Paul在“半人间”酒吧学习调酒，并在每天的工作及进进出出的酒客当中，阅览和经历一个又一个人生故事，引领观众在甜、酸、苦、辣的酒杯中，调制出最适合自己的人生鸡尾酒。 paul的故事 paul和酗酒及患肝癌的父亲一向势如水火，有日父子为前途问题打架，父亲中风而死。paul开始自力更生。起初，他非常恨父亲。而这一晚，paul开始想多了解父亲一点。他企图从唯一的线索“酒”中寻回父亲。他走进“半人间”应征服务员，开始学习调酒。 老板与阿权的故事 老板与阿权经常来酒吧，老板每天都喝醉，要阿权背他离开。阿权是酒吧里唯一一个不是自愿来的客人。他每晚被老板逼来陪饮，但他十分尊敬老板，从来不甘逆他意。老板却从来看不起他，还对他出口侮辱。阿权经常陪老板，冷落了女友Macy。有日，Macy终于...

故事講述18歲的Paul中五畢業後到一間名叫半人間的酒吧應徵調酒師，老闆娘Candy竟二話不說聘用了零經驗的他。Paul正式工作後認識了另一名調酒師Stella，二人互有好感，感情經過重重波折。而在酒吧工作，令Paul觀察到客人飲酒前及飲酒後的神情，體現了人生百態。

The melancholy Candy runs the Half Mortal, a trendy bar in Hong Kong. She hires Paul; Stella, a part-time employee who's a college student in psychology, trains him. He has a gift for mixing the perfect drink to fit each customer's emotional needs. His own emotions, however, are complex: his father, an alcoholic, has died recently; he's abandoned his studies; and, although he's likes Stella, he's a tyro with women and inarticulate with her. Is alcohol the key to happiness, as Paul wonders; does it simply change peoples' personality, as Stella thinks; or, is it just there, as Candy's business sense tells her? Can Paul and Stella blend into something smooth?