The Boxcar children uncover a mystery when they compete in several contests at the county fair.

While visiting a friend in New York City, the Aldens investigate the theft of a valuable diamond.

While staying at the Crooked House, the family home of their housekeeper Mrs. McGregor, the Aldens try to solve a riddle that will lead them to a hidden treasure.

The Aldens investigate a mystery involving a legendary mining expedition to the gold fields of Alaska.

The Boxcar children must track down an instrument thief in time to save Greenfield's music festival from disaster.

While visiting their cousin's pineapple plantation in Hawaii, the Aldens hear a local legend about a black pearl with a curse on it and investigate mysterious incidents on and around the plantation.

The Alden children suspect someone of trying to sabotage the local dog show.

On a camping trip to Arizona with their grandfather, the Alden children search for a lost gold mine.

When the Alden children accompany their grandfather on a trip to Seattle, they discover clues throughout the city, seemingly planted just for them.