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 Aldens search for carousel horses that have disappeared from an amusement park.

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

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.

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

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 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.

The Aldens investigate the rumors of ghosts, disappearing props and a haunted seat in the Trap-Door Theater.

The Boxcar Children are going to a dog show. They meet all kinds of dogs, from a spotted Dalmatian to a big, hairy sheepdog. But then strange things start happening at the dog show, and no one knows why. Can the children solve the mystery and save the day?

When their favorite pizza restaurant almost goes out of business, the Alden children try to help their friends stay open while they find out who is behind all their problems.