The Heffley family prepares to go on a road trip, but Greg doesn't want to go as things are bound to go wrong. A family road trip is supposed to be fun... unless you're with the Heffleys of course. The journey starts off full of promise, then quickly takes several wrong turns. Petrol-station bathrooms, crazed seagulls, a fender bender, car accidents and a runaway pig - not exactly Greg Heffley's idea of a good time. But even the worst road trip can turn into an adventure - and this is one the Heffleys won't soon forget. Greg gets treated like a pet at a vets office, when he is bitten by a pig and some items are supposedly stolen by "the Beardo's." Mom makes her own snack pack called the Mommy Meal and Greg soon finds out all these crazy things Mom is doing, is coming from a weird magazine called Family Frolics magazine. Will Greg make it home alive or not?