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.

While traveling by trailer in upstate New York to find a runaway, Trixie Belden and Honey Wheeler investigate a case of mysterious trailer thefts.

While spending Christmas break at an Arizona dude ranch, Trixie and the Bob-Whites work to solve several mysteries--a phony cowboy, disappearing staff, and puzzling cries in the night.

Thirteen-year-old Trixie Belden and her friend Honey make several trips to the local marsh in search of herbs and flowers to replace their teacher's plant specimen collection and to look for the pirate treasure that is rumored to be hidden there.

While vacationing at her uncle's lodge in the Ozark Mountains, Trixie and the Bob-Whites explore caves looking for the ghost cave fish, a rare species wanted by a national science magazine.

When the Bob-Whites--minus Dan--head to Cobbett's Island to spend ten days in a historic home on the beach, Trixie finds an old letter tucked away in a book and sets off on a long-delayed treasure hunt.