To Greg Heffley, middle school is the dumbest idea ever invented. It's a place rigged with hundreds of social landmines, not the least of which are morons, wedgies, swirlies, bullies, lunchtime banishment to the cafeteria floor - and a festering piece of cheese with nuclear cooties. To survive the never-ending ordeal and attain the recognition and status he feels he so richly deserves, Greg devises an endless series of can't-miss schemes, all of which, of course, go awry. And he's getting it all down on paper, via a diary - "it's NOT a diary, it's a journal!" Greg insists, preferring the less-sissyfied designation - filled with his opinions, thoughts, tales of family trials and tribulations, and (would-be) schoolyard triumphs. "One day when I'm famous," writes Greg, "I'll have better things to do than answer people's stupid questions all day."

When Greg Heffley's dad threatens to send him to military school if he doesn't stay out of trouble, Greg finds all-new ways to land himself in the doghouse! For starters, Greg's in over his head when he pretends to work at the swanky country club where Rowley's family has a membership. Things don't go much better on a father-son camping trip with the Wilderness Explorers, and then there's the Heffley's new dog, Sweetie, who fetches even more trouble for Greg.

Greg Heffley and his family escape to a tropical island resort for some much-needed rest and relaxation, but sun poisoning, stomach troubles, and venemous creatures all threaten their vacation.