Some Too Quiet Gentlemen (1973)

Original title: Quelques messieurs trop tranquilles

The sleepy little village of Loubressac is well on its way to becoming a ghost town. To save the town, the local citizenry hatch a plan to attract tourists. To their horror, the plan misfires when a group of hippies are the first to move in. The hippies' free and unconventional ways quickly upset the staid lives of the locals. Then one of the locals is found murdered, and suspicion inevitably falls on the newcomers. Eventually, the locals and the hippies join forces to solve the mystery, and in the course of their adventures learn to respect each others' ways.