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 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.

When their favorite pizza restaurant almost goes out of business, the Alden children try to help their friends stay open while they find out who is behind all their problems.

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.

In this all-new very special mini-series, the Aldens have been recruited by a secret society to return lost artifacts and treasures to their rightful locations—all around the world! After finding a painted turtle figurine, the Aldens are introduced to the Silverton family and Reddimus Society, a secret guild whose mission is to return lost artifacts and treasures to the sites they were taken from. The Aldens board a private train to New Mexico

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While on a bicycle trip to their aunt's farm, the four Aldens help solve a mystery.

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!

When Henry's magic teacher, The Amazing Arthur, goes missing right before the Greenfield Magic Shop's annual magic show, Henry and his sibilings look into Arthur's disappearance.

A young Canadian visitor helps the Alden family solve a mystery involving a lost coin collection.

The Boxcar Children know how much work it takes to live in the wilderness. They also know how much fun it can be! The children love exploring and learning new things at a primitive skills summer camp. But when strange things start happening around the camp, they need to use another of their favorite skills-- mystery solving!