After a storm blows through Sleepyside and damages the Bob-Whites' clubhouse, Trixie and Honey take a job patrolling the game preserve and find evidence of a poacher.
While organizing an ice carnival to raise funds for her pen pal's school library, Trixie investigates a mysterious problem facing Regan and a run of thefts and accidents in the neighborhood.
When the Bob-Whites head to Cobbett's Island to spend ten days in an historic home on the beach, Trixie finds an old letter tucked away in a book and sets off on a long-delayed treasure hunt.
When Trixie Belden and Honey Wheeler find a cut diamond embedded in the dirt floor of the old abandoned gatehouse, they set out to find whoever left it there.
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.
The Bob-Whites, plus their friends from Iowa, add detective work to their New York City sightseeing trip after Trixie helps a stranger and receives, as thanks, a purse containing a cryptic prophecy and a promise of great fortune.
