When he was a newborn baby, Edith Guetz thoughtlessly told her son Tanguy : "If you want to, you can stay at home forever". 28 years later, the over-educated university teacher of Asian languages and womanizer leads a successful and wealthy life... while still living in his parents' home. Father Paul Guetz longs to see his son finally leave the nest, a desire that his wife does not share. Edith finally agrees and the pair unite to make Tanguy's life at home miserable. However, they don't know that Tanguy isn't the type of guy who easily gives up.