On getting engaged, Thomas (Max Boublil) meets his future father-in-law Gilbert (Alain Chabat), married for 30 years to Suzanne (Sandrine Kiberlain). Gilbert, disillusioned, feels that he missed out on life by getting married. He persuades Thomas not to marry his daughter Lola (Mélanie Bernier) and to dump everything along with him. They then dive into a wild new life as big kids, convinced that freedom lies elsewhere. But what is the cost of recovering your teenage dreams?