Fred borrows money from Mr. Slate to fix up his backyard for a long weekend. He plans to spend the whole weekend in Bedrock with his family and the Rubbles. But Gazoo invites the Rubbles and Flintstones to spend the weekend in the 25th Century A.D. instead. Among the many marvels they encounter: a descendant of Mr. Slate who still wants back the money Fred borrowed that weekend, plus interest.