L'Emmerdeur (2008)
Directed by Francis Veber

Film Synopsis

Ralph Milan is a professional killer who is a master of his art.  His next target is Randoni, an important witness in a corruption trial due to take place at the Palais de Justice in Nice.  With his customary professionalism, Milan checks into a hotel and gets himself a room looking out onto the entrance to the law courts, the perfect vantage point from which to execute his mission.  Meanwhile, in an adjoining room, press photographer François Pignon is preparing to kill himself.  Devastated by the news that his wife Louise has left him for another man, Dr Wolf, François has decided that his life is worthless, so he plans to hang himself from a water pipe in the bathroom.  The pipe comes free and the next thing François knows he is being drenched in water.  Within a matter of seconds, the flood has spread to Milan's room next door, instantly putting the kibosh on his meticulously planned assassination.

The soggy fracas attracts the attention of a passing bellboy, whose first thought is to call the police.  Milan naturally has his own reasons for wanting to keep the cops out of this, so instead of involving them he offers to keep a close eye on François and make sure he doesn't repeat his suicide attempt.  François mistakes Milan's interest in him as genuine concern.  Believing he has found a real friend, he insists on sticking to him and assisting him in whatever line of work he is in.  Far from acquiring a helpful ally, the unfortunate hitman soon discovers he has landed himself with the most infuriating of sidekicks.  If Milan's talent is killing people, François's is an unerring ability to drive perfectly sane people out of their mind...