Jonas, a 40 something Parisian, is still desperately in love with his ex-girlfriend Léa. When he knocks on her door to confess his feelings and she turns him down, he ends up at the café downstairs.　　Inspiration strikes and he sits down to write her a long love letter, dodging everything he was supposed to do that day. What begins as a last attempt to get her back surprisingly turns into a vivid musing on the state of his life.　　Over the course of a day, helped by a wisecracking bartender and an array of patrons from the neighborhood, Jonas has to face his past relationships, his uncertain future and, most of all, himself.

　　故事发生在法国和比利时的边界，鲁本（贝诺特·波尔沃尔德 Benoît Poelvoorde 饰）和马塞尔斯（丹尼·伯恩 Dany Boon 饰）是分别隶属于比利时和法国的海关边境检查员。个性刚烈又倔强的鲁本是个坚定的民族主义者，他对关于法国的一切嗤之以鼻，其中当然包括法国人马塞尔斯，而他并不知道的是，马塞尔斯和自己的妹妹露易丝（Julie Bernard 饰）之间产生了真挚的感情。　　1993年的到来彻底改变了鲁本和马塞尔斯之间井水不犯河水的关系，边境检查站被取消了，两人成为了整天抬头不见低头见的同事兼搭档，在矛盾和对抗之间，马尔塞斯也再也无法隐瞒他和露易丝之间的恋情。一场“世界大战”即将拉开序幕。