The Aldens investigate when the arrival of several suspicious characters in Greenfield coincides with a mystery involving a popular boy actor.

The Alden children help out a storeowner at the Hope Harbor Mall and discover that someone is tampering with the merchandise shipments.

While the Aldens are visiting a friend of Grandfather's at the beach, Benny finds a long-lost piece of a map to a legendary pirate treasure, a discovery that brings unwanted attention from fortune hunters.

The Aldens try to help a visiting Russian gymnast who is surrounded by mysterious people and events and who seems to have a secret.

The Aldens help a farmer whose honeybees have stopped producing honey and discover a sabotage scheme.

The Aldens, while testing the latest version of their favorite computer game, are surprised to find messages directed specifically at them.

While visiting the Outer Banks of North Carolina, the Aldens see a mysterious wild horse that may be a ghost.

A series of practical jokes at a restored nineteenth-century farmhouse makes the Aldens wonder if the ghost of its builder is at work.

The Aldens accompany their grandfather to his class reunion and investigate the possibility of a buried Civil War treasure, and of a ghost in the bell tower, at Goldwin University.

While visiting a small town in Alabama, the Aldens hear mysterious howls at midnight, leading them to wonder if an old local legend about a ghost dog is true.