The Alden children hunt for their late grandmother's necklace that has been missing for years.

While on a cruise with their grandfather, the Alden children help discover who is behind the mysterious troubles of the ship--disconnected phone lines, engine trouble, a man overboard--and still have fun sightseeing, eating, and swimming.

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

The Alden children plan to ride in their boxcar at the Greenfield Founders' Day Parade, but the newly refurbished boxcar is stolen a couple of days before the big event.

The Alden children uncover a plot to sabotage the Greenfield Bears baseball team. Includes baseball puzzles and activities.

While visiting the Florida Keys, the Aldens encounter suspicious characters, strange incidents at night, and a plot to steal valuable coral.

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.

The Alden children investigate various mix-ups at a zoo run by their grandfather's friend in an effort to save it not only from pranksters but also from the town council.

At an old library, the Alden children discover a boy who needs their help and a stranger who is after a valuable object they found in the library.