Hoping to bring his family closer together and to recreate his childhood vacation for his own kids, a grown up Rusty Griswold takes his wife and their two sons on a cross-country road trip to the coolest theme park in America, Walley World. Needless to say, things don't go quite as planned.

Upon learning that their mother has been lying to them for years about their allegedly deceased father, two fraternal twin brothers hit the road in order to find him.