Charlie Brown is taken aback during class when he learns that he and Linus have been chosen for a student exchange program. Eager to get ready, he leaves school and happily invites his loyal companions, Snoopy and Woodstock, to join him on this adventure. The surprises keep coming as Charlie discovers a letter in the mailbox addressed specifically to him, written in a peculiar language.
Moments later, Charlie receives a call from Peppermint Patty, who shares that she and Marcie have also been selected for the program, and they’ll be on the same flight as Charlie and Linus. At the airport, their friends gather to bid them farewell, with most cheerfully shouting, “Bon Voyage, Charlie Brown!” while Lucy chimes in with a teasing, “And don’t come back!” It’s revealed at the ticket counter that Snoopy has astonishingly secured a First Class ticket, leaving everyone else in economy class in disbelief.
During the flight, Charlie reveals the letter he received, which originates from France. Since Marcie has been studying French, she offers to translate it. The letter seems to welcome Charlie and hints at the opportunity for him to stay at the Chateau Mal Voisin (“The Chateau of the Bad Neighbor”). The mysterious sender, Violette, is someone Charlie doesn’t recognize.
Upon landing in London, England, the group enjoys some lunch while Snoopy takes to the tennis courts at Wimbledon for a brief match. From there, they board a train to Dover, eventually taking a hovercraft to France. Once in France, the group rents a car with Snoopy at the wheel. Their first destination is Morville, where Peppermint Patty and Marcie will be hosted by a family that includes a son named Pierre. As Charlie, Linus, Snoopy, and Woodstock set off, the girls explain their whereabouts, but upon hearing about the Chateau Mal Voisin, Pierre grows anxious, warning that no one goes to that place and the owner would never invite anyone.
Attempts to contact the chateau yield no response, leading them to decide to wait until morning. Meanwhile, Charlie, Linus, Snoopy, and Woodstock navigate the rain-soaked town of Le Heron and pass by both a school and a pub until they glimpse the ominous silhouette of the chateau. Finding no one home, they resort to camping in nearby stables. Snoopy is on watch, but once Charlie and Linus drift off to sleep, he and Woodstock sneak away to a local pub for some root beer. When dawn breaks, Charlie and Linus awaken to find themselves covered with blankets and a delicious meal lovingly prepared for them, hinting at the whimsical adventures yet to unfold.
