Mr. Clue gets on a train ready to start his vacation, but when a famous actress is robbed during the trip, it is up to Mr. Clue to find the culprit.

While living out west for the summer with their Aunt Jane, orphans Henry, Jessie, Violet, and Benny Alden's friend Mike Wood's house burns down and he is blamed for starting the fire.

While staying at a hotel in New York City, the Aldens investigate a series of annoying pranks plaguing the management and guests.

A family, snowbound in a vacation cabin, discovers adventure in surrounding wild life, three children they find in the snow, and a search for a lost recipe.

The Alden's search for carousel horses that have disappeared from an amusement park.

A lost dog finds the Alden children when they have to take shelter in an old, abandoned house while on their way for an overnight bicycle trip.

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

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.

After Detective Dinosaur and Officer Pterodactyl find a missing baby and a home for Cadet Kitty, they lose and find each other.

During a storm, orphans Henry, Jessie, Violet, and Benny Alden make a red boxcar their home that keeps them safe and warm.