La cuirasse (2002)

One evening, Chris finds Margot at his door, distraught and in need of a place to sleep. He lets his former lover in, but after just one night she decamps without explanation. Very soon, Chris learns in the harshest possible way that Margot is on the run from Matthias, a powerful gang leader, from whom she stole something immensely valuable. The race is on to track down Margot. Chris has a solid reputation in the criminal underworld, and relies upon a network of buddies spanning the whole country. Matthias can also count on a team of loyal operatives, and has largely enough money to fund a personal war. But outside their Parisian stomping grounds, both Chris and Matthias must contend with other redoubtable players...