During the 1920s, Billy, Finn, and Dannie, living in a railroad workers camp in the Cascade Mountains, encounter Finn's air show pilot uncle, endure a troublemaking new boy, and stand up to smugglers.
Some of Donna Jean's family are so sure she will fail in reciting a poem at a school program that they almost convince her of her inadequacy, until her uncle's belief in her helps her to try again.
Not long after her family becomes wealthy, Diana Lynch's long-lost uncle appears and starts ruining her social life, causing Trixie Belden to investigate whether Uncle Monty is an imposter out to steal the Lynch fortune.
In 1849 eleven-year-old Luke leaves his family's farm home in Iowa, accepts his uncle's offer of a chance for an education, and travels with his relative to Boston.
When Alfredo, a twelve-year-old choir boy in eighteenth-century Italy, loses his family in a fire, he goes to live with Uncle Giorgio, who he discovers is a sorcerer in control of the fires of Mt. Etna with sinister plans for his nephew.
Teddy is not thrilled with the present his uncle gives him for his tenth birthday--a camping trip for him and his younger brother--but on his first outing away from San Francisco's Chinatown, Teddy learns some interesting facts about nature, about his uncle, and about himself.