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.
Trixie suspects someone of trying to sabotage the pet show that she and the Bob-Whites are staging in order to raise money to feed the starving game-birds.
While preparing for a fund-raiser antique show, Trixie and the other members of the Bob-Whites discover a secret code in the pages of an old magazine in the attic.
Vacationing on a Minnesota horse ranch, Trixie and her friend, Honey investigate the reported sightings of a legendary ghost and join the search for a missing Arabian horse.
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.
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.
While on a trip to St. Louis, fourteen-year-old Trixie Belden discovers some mysterious papers in her hotel room and soon realizes that she and her friends are being followed as they cruise in a towboat down the Mississippi River.
Participating in an archaeological dig on an Indian burial ground, Trixie suspects a greedy, treasure-hunting college student of burglarizing several mansions in the area.
While vacationing at her uncle's sheep ranch, Trixie and the Bob-Whites track down the thieves who are behind the mysterious disappearance of several sheep.