阿凡（余文乐饰）自小便没有了父母，为了生活与好友阿明（黄又南饰）在戏院门口卖蔗。一天他们看到在街头上大打狮鼓的阿蓝（蔡卓妍饰）。阿明对阿蓝一见钟情，决定与阿凡一起到阿蓝父亲（葛民辉饰）的武馆以学艺为名接近阿蓝，阿蓝却对阿凡有意，阿凡决定成全好朋友，渐渐与阿蓝生疏了。

Set in 70s Hong Kong, Just One Look actually tells of Fan (Shawn Yu), whose policeman father commits suicide in a cinema toilet, but Fan believes he was murdered by a gangster nicknamed 'Crazy' (Anthony Wong). Ten years later Fan contemplates avenging his father's death. Meanwhile, he and best friend Ming (Wong Yu Nam), who are movie fans and sell their family wares outside the local cinema, decide to enlist for kung fu lessons after spotting the master's beautiful daughter (Charlene Choi). But Fan falls for a mysterious girl who lives in the countryside (Gillian Chung).