Greg Heffley has always been in a hurry to grow up. But is getting older really all it's cracked up to be? Greg suddenly finds himself dealing with the pressures of boy-girl parties, increased responsibilities, and even the awkward changes that come with getting older—all without his best friend, Rowley, at his side. Can Greg make it through on his own? Or will he have to face the "ugly truth"?

Whatever you do, don't ask Greg Heffley how he spent his summer vacation, because he definitely doesn't want to talk about it. As Greg enters the new school year, he's eager to put the past three months behind him . . . and one event in particular. Unfortunately for Greg, his older brother, Rodrick, knows all about the incident Greg wants to keep under wraps. But secrets have a way of getting out . . . especially when a diary is involved.

Let's face it: Greg Heffley will never change his wimpy ways. Somebody just needs to explain that to Greg's father. You see, Frank Heffley actually thinks he can get his son to toughen up, and he enlists Greg in organized sports and other "manly" endeavors. Of course, Greg is able to easily sidestep his father's efforts to change him. But when Greg's dad threatens to send him to military academy, Greg realizes he has to shape up . . . or get shipped...