The Boxcar children investigate when ice cream and other items start disappearing from their favorite ice cream parlor.

The Alden children suspect someone of trying to sabotage the local dog show.

When the Alden children accompany their grandfather to the Snow Haven Lodge, a series of odd occurrences threaten to disrupt the annual winter games.

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.

The Alden children have another mystery to solve when they visit a castle and must figure out which of the guests has stolen the Stradivarius violin.

The mysterious disappearance of a reclusive neighbor's cat involves the Boxcar children in some complicated detective work.

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

When an elderly friend is injured, the Alden children offer to help him with his window-washing business in their small town of Greenfield and agree to help him solve a riddle that has arrived in a mysterious invitation.

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.

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