Greg records his sixth grade experiences in a middle school where he and his best friend, Rowley, undersized weaklings amid boys who need to shave twice daily, hope just to survive, but when Rowley grows more popular, Greg must take drastic measures to save their friendship.

Greg Heffley tells about his summer vacation and his attempts to steer clear of trouble when he returns to middle school and tries to keep his older brother Rodrick from telling everyone about Greg's most humiliating experience of the summer.

Middle-schooler Greg Heffley nimbly sidesteps his father's attempts to change Greg's wimpy ways until his father threatens to send him to military school.