Every summer, the Billionaire Tranchant and his wife Eliane host the glamorous world of celebrities in their luxurious mansion in the south of France. When a criminal car sabotage related to threatening letters wreak havoc in the villa, Tranchant goes in search of the best agent for the investigation. In the middle of this hot summer, only the arrogant and incompetent agent Boullin is available... To catch the suspect and solve the mystery, he will have no choice but to impersonate a newly hired butler and will turn everyone's vacation into a hilarious game of 'Cluedo'!