The Aldens climb a mountain and find a mystery! The hike up Old Flat Top was only supposed to take a day, but a dangerous rockslide changes everything to reveal a hidden cave that just may hold a legendary treasure!

The Alden family rents a houseboat to drift down the river, and encounters a mystery in the little towns along the river, involving a fast black car.

The Aldens visit the shore in New Jersey and help out at an amusement pier that is rumored to be unsafe.

"The Aldens are at Wildcat Crossing, a recreated frontier town full of cowboy fun. But when horses disappear and other pranks threaten to ruin the Wild West show, the Boxcar Children must find out who's the varmint causing all the trouble"--

Helping Grandfather's friend, Mr. Yee, who has broken his arm and cannot tend a beloved vegetable plot, the Alden children begin investigating when they discover that vegetables have gone missing and that someone is vandalizing the garden.

Four orphaned siblings, determined to stay together as a family, decide to inhabit an abandoned boxcar and turn it into their new home in the woods. When one of the siblings falls ill, the others go out to seek a doctor to save their sister. Meanwhile, their wealthy grandfather has offered a sizable reward to anyone who has information about his grandchildren, hoping that they can all be reunited once more. As the children continue to evade being...

"The winter sports season is here, and the Aldens are excited about all the snow activities--especially snowboarding. But soon they find themselves in the middle of a mystery surrounding a star athlete and a stolen snowboard"--

Because they do not want to be separated, four orphaned children run away and live in an old abandoned boxcar

The Aldens visit an old camp in Quebec, Canada, and begin to suspect that someone or something is trying to scare them away from the place.