Two brothers, Julien (25) and Louis (12) work and live on a barge on the Seine in the heart of Paris. They transport gravel and make a little money on the side through petty theft. They've grown up alone, bonded together by the course of the river.
A Slav stolen goods dealer proposes a big job: to steal The Blonde with Bare Breasts by Manet, exhibited at the Orsay Museum. Louis, responsible for the theft, manages the unthinkable and brings the famous painting back to the barge. But one of the museum security guards, Rosalie, an easy going kind of girl, has followed him. The three get into a fight and the two brothers lock Rosalie in the barge's hold and set sail, all three now on the run.
At Joinville le Point, the adventure takes a different turn when Rosalie escapes from her prison and makes a most unexpected offer to her kidnappers.