When one person asks another person "Do you dare?", the other person must say "dare", this is the rule of the game. The encounter between the little boy Julien and the little girl Sophie began with such a children's farce, and an exquisite iron box was the witness of their game. Swearing, disrupting the class, peeing in the principal's office, wearing underwear outside... The two of them played a game for more than ten years, and they dared to do anything except admit that they loved each other. Sophie (Marion Cotillard) proposed that they separate for four years, and the content of the challenge was whether Julien (Guillaume Canet) dared to hurt Sophie. Four years passed in a trance, and Julien found Sophie. In order to proceed with the game, he decided to marry someone else and invited Sophie to be a bridesmaid. The hurt Sophie threw the iron box at Julien's wedding, "Do you dare to regret the marriage?" The closest friends hurt each other the most. The two people who were equally heartbroken agreed to separate again for ten years. In the past ten years, Julien has everything, family, career, friends, but without Sophie, it's like losing his heart. It turns out that life without passion is so boring. Finally, ten years have passed, "Love me, ifyoudare..."