Roubaix is an industrial city in northern France. At the end of the year, full of incidents like any other day, Police chief Daoud and the ambitious newcomer Louis are busy dealing with crime scenes, from arson to robbery. The two men investigating an old lady's murder, suspected the old lady's neighbors, Claude and Marie, they may have been a witness in another incident. They separate and interrogate them differently.

Arnaud Desplechin's continued interest in public authority and its performance is not difficult to find in Oh Mercy! , which is the main plot of the process by which the two police investigate and resolve crimes. Under the apparent influence of Dostoevsky F.’s Crime and Punishment and the American police investigations of the 50’s, Oh Mercy! offers more than a crime thriller, showing the charisma of Roschedy Zem portraying Police chief Daoud and the presence of Léa Seydoux and the camera that captures various locations in Roubaix. Roubaix is the hometown of DESPLECHIN and is notorious for the high crime rate. (Jin PARK)