The Aldens start a business producing birthday parties and find themselves investigating a series of robberies taking place during their parties.

Benny wants adventure and finds it as he and the other Alden children help uncover the plan of those who would prevent ballooning from coming to Lloyd's Landing.

The Alden siblings continue their mission to return lost artifacts around the world by visiting the Great Wall of China and an elephant reserve in Thailand, among other sites, but halfway around the world trouble seems closer than ever.

The Boxcar Children are helping at a pizzeria, but it seems that someone is trying to shut it down. Can they find out who is causing trouble?

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 Aldens are excited when a new store called the Game Spot opens up in town, but after a series of robberies at the other stores in the mall, the siblings have a new mystery to solve.

Can the Aldens figure out who's responsible for the bad press before the center gets shut down for good? Henry, Jessie, Violet, and Benny are excited to learn more about raptors when they volunteer at a rehab center for wild birds. But not long after they arrive, a series of strange events makes it seem like someone might be trying to sabotage the center. Who could the culprit be, and why would they want to cause trouble for injured birds?

When the Alden children accompany their grandfather to the Snow Haven Lodge, a series of odd occurrences threaten to disrupt the annual winter games.

When the children find a letter written in riddles in Aunt Jane's attic, they believe it may contain clues to a hidden treasure on the island, but they soon discover they are not the only ones treasure hunting.

The Aldens become involved in a community theater production of "The Wizard of Oz," which is systematically and mysteriously being sabotaged.