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.

Someone is trying to put Aunt Jane's motel out of business, but the Alden children aren't going to let that happen.

When the Aldens help a friend of their grandfather's to build the world's largest yo-yo, they soon discover that more than one person is trying to prevent them from finishing the job--and for more than one reason.

While on a camping trip with their grandfather, the Alden children try to find out about the loud music and missing food that threatens to scare away other campers.

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.

When their grandfather arranges for them to spend two week at Sunny Oaks, the four Alden children enjoy settling into the routines of farm life but become suspicious about a mysterious horse locked in the stables.

While staying at an eighteenth-century inn in Vermont, the Boxcar children become curious about the mysterious "accidents" that keep plaguing the owners.

"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? Adapted from Gertrude Chandler Warner's story of the same name, this early reader allows children to start reading by themselves with a Boxcar Children classic."--Amazon.

Six children help solve the mystery of a missing spyglass that has kept two brothers feuding for years.

A friendly writer with a metal detector, the mysterious inhabitants of a tower house, and the discovery of a locket in the sand are ingredients for the Aldens' latest mystery.