What is the main content of the movie "Love Me If You Dare"?

The film begins at a construction site, and workers are tearing down an old building. The camera wandered over the construction site and showed us an old candy box that was half frozen in the foundation. A little boy's voice sounded. He said that at that time, there was a game specially for children, called "Great Adventure". When one child asks another child "Dare", the latter has to say "Dare". On the streets of France 80 years ago, the camera flew backwards, retreated behind the windshield of a school bus, then exited the school bus and appeared outside the rear window, followed by several books cut into a dark place and then pulled out. It turned out that we were still in our schoolbag just now. When the camera was turned on again, we saw a little girl's face, followed by a sharp retreat. We saw the little girl surrounded by a group of children. The little boy company met the little girl Sophie in front of the school bus. Sophie, a Polish immigrant, was bullied by all the children. Julian said he liked Sophie, and Sophie's answer was, "Then prove it to me. Do you dare?" Even when the driver was not in the car, he pushed the handbrake and the car rushed down the slope, with the driver chasing after it. Julian and Sophie became friends at the cost of being beaten by their father. Since then, the two children have started an endless game of "daring". They don't believe in any rules. The world is a huge playground: they make up words and swear in class; Spray the teacher with ink; Peeing in the principal's office; Make the bride cry at her sister's wedding ... Although their games are not only fun, they often bring great risks. They enjoyed it, but this habit didn't change until they grew up. They dare to do anything but admit that they are in love. The days have passed in endless mutual provocation, and it has been 20 years before you know it. At his wedding, she came to ask him if he would break his word. The wedding was ruined and they fell out. This time, the challenge of "dare" is not to see you for ten years. Ten years later, she called him and asked him if he dared to elope. He left his wife and children immediately. When she arrived, it was actually another "challenge" game. She made the house look like a robbery scene to see if he dared to leave ten minutes after she called the police. I played this time. ...