The Alden children visit Mystery Ranch, a man in a blue hat appears, Mike's house burns down, and the uranium mine is in danger.

"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"

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!

Henry, Jessie, Violet, and Benny Alden spend a summer full of adventure and surprises while camping on their own private island.

The Boxcar Children investigate a mystery about a rundown yellow house on Surprise Island and the man who disappeared from it.

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!