Cloportes (1965)

Original title: La Métamorphose des cloportes

Three little criminals get a tip for a great coup with lots of money in it. Unfortunately they lack the starting funds to buy the required welding torch. So they persuade their successful colleague Alphonse to join their team. But the well thought-out coup fails, and Alphonse is the only one of them who ends up in jail for several years. When he's released, he's out for revenge.