The Surete Commissioner assigns Inspector Clouseau and Sergeant Deux-Deux to spend a night in the Louvre gallery in hope of catching the Blotch, a notorious art thief, in the act of stealing paintings. The Blotch looks like an ink blot and can change his form to blend into any surroundings, and Clouseau and Deux-Deux are unable to locate him even as he swipes huge paintings from behind their backs and loads the paintings onto a truck. The Commissioner is furious when the Louvre is entirely fleeced and orders Clouseau and Deux-Deux to repaint every missing masterpiece!