Having every reason to be happy, forty-three-year-old father-of-one Guillaume Canet sees his world turn upside down when Camille, his young and fresh co-star, makes him feel like a sad has-been. Now, bent on proving her wrong, insecure Guillaume is eager to go to extreme lengths to change everything and regain his long-lost sex appeal, of course, behind the back of his significant other, Marion Cotillard. However, as the situation spins out of control, a drastic, uncontrollable transformation takes place, much to the horror of the cast and crew. But, above all, Guillaume wants to be cool again. How hard can it be?