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

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

While canoeing and backpacking near Timberwolf Lake, the Aldens receive strange warnings to stay away from the area and stumble upon clues to a missing cache of stolen coins.

Henry, Jessie, Violet, and Benny are orphans. Determined to make it on their own, they set out to find a safe place to live. They discover an old, red boxcar that provides shelter from a storm. Against all odds, they make it into their home--and become The Boxcar Children.

The Alden children find mystery and adventure as they journey along the Little North Railroad in two cabooses rented for the summer by their grandfather. The Alden children find mystery and adventure as they journey along the Little North Railroad in a caboose rented for the summer by their grandfather

When the Alden siblings visit their grandfather's friend in an apartment building, they begin to wonder about the many mysterious events that keep happening on the thirteenth floor of that building.

When the Alden children spend a week visiting at Pilgrim Village, they uncover the mystery behind the unusual happenings at the historic site.

The Alden children have an adventure as they journey along with the Little North Railroad in two cabooses rented for the summer by their grandfather.