The Griswalds, consisting of Clark, Ellen, and their two children Rusty and Audrey, win a game show called "Pig in a Poke" and their prize is a two-week trip to Europe. They start their journey in London, where they mistakenly drive on the wrong side of the road and get into multiple mishaps, including hitting Stonehenge with their rental car.
They then move on to Paris, where they struggle with the language barrier and get into more trouble when Rusty accidentally paints a nude woman into the background of a family portrait at the Louvre.
Next, the family travels to Germany and stays with their distant relatives, the Griswold family, who turn out to be snobbish and uninterested in spending time with them. The Griswalds visit Oktoberfest, where Clark gets drunk and embarrasses the family.
In Italy, they hire a thief named Enrico to be their tour guide, who steals from them throughout their trip. They also accidentally drive on a restricted road in Rome and enter a festival where Audrey is crowned as the Queen of a beauty pageant, despite not knowing a word of Italian.
On their last day of the trip in England, the Griswalds visit Stonehenge again and accidentally knock over the stones, leaving them with a hefty repair bill.
Despite the mishaps and challenges, the Griswalds eventually bond as a family and return home with memories that they will never forget.