Boys don't keep a personal diary. Or are they? Greg Heffley is in school and his life is not easy. They call him to the board on the very day when he... well, didn’t finish something. And during breaks and after classes he is surrounded by tall, scary, angry high school students. The girls giggle at him and even notice the tiny pimple that popped up behind his ear. No one understands how difficult Greg's life is: neither his parents, nor his close friends. When Greg's friend Rowley suddenly becomes popular, Greg tries to take advantage of his popularity and benefit himself. However, Greg, unwittingly, with his actions causes a chain of events, because of which the boys' friendship will have to undergo a test of strength.