"It's a new school year, and Greg Heffley finds himself thrust into middle school, where undersized weaklings share the hallways with kids who are taller, meaner, and already shaving. The hazards of growing up before you're ready are uniquely revealed as Greg records them in his diary. Greg is happy to have Rowley, his sidekick, along for the ride. But when Rowley becomes popular, Greg tries to use his best friend's newfound popularity to his own...