Henry, Jessie, Benny, and Violet Alden meet Mike Wood and a strange chain of events begins. Mike's house is mysteriously burned down, a man in a blue hat appears, and the Alden's uranium mine is in danger of being sabotaged. The four youngsters solve the mystery.

"The Aldens spend the summer on their aunt's ranch! The ranch is a beautiful place, but it's also the source of trouble between Aunt Jane and Grandfather. As the Boxcar Children explore the land, they make an amazing discovery. Will it help mend Aunt Jane and Grandfather's relationship?"--Publisher's description.

"The Aldens spend the summer on Grandfather's island! Joe, the island's friendly handyman, helps them with anything they need, but as the children continue to explore their summer home, they realize there is more to the island--and to their new friend--than meets the eye."--Publisher's description.

The Alden children and their grandfather are hiking down from Flat Top when a rockslide reveals a cave with a big secret.

The boxcar children travel to Maine, take canoes into the wilderness and live in a house exactly like the one on Surprise Island, except the Maine house is brown, not yellow. They untangle the mystery of the two houses. Relates the exploits of the four Alden children as they locate a missing man. The Boxcar children are determined to solve the mystery that surrounds an old yellow house on their grandfather's property. Strange things have happened...

The Alden children travel on a Mississippi paddle-wheel steamer to visit an old family friend in his cabin near Hannibal, Missouri, and try to discover who is responsible for the mysterious activities near the house.

While visiting the seaport town of Ragged Cove, Massachusetts, the Alden children find the ship's log of the Flying Cloud, shipwrecked in 1869, supposedly during a mutiny.

Jessie wants her science fair project to make a difference. So when she gets the chance to test a local creek for pollution, she can't wait to get started. But when things start going wrong with her experiment, Jessie and her siblings don't just have an experiment to investigate, they have a mystery to solve!

The Alden children travel on a Mississippi paddle-wheel steamer to visit an old family friend in his cabin near Hannibal, Missouri, and try to discover who is responsible for the mysterious activities near the house.

The Alden children save an old woman's house, land, and all the animals in her animal shelter from greedy contractors.