The Alden children take a cruise with their grandfather, while sightseeing they also explore the mystery behind some engine problem, a man overboard, and other troubles on the ship.

The Boxcar Children go camping with their grandfather and end up investigating who's behind the missing food and loud music that's scaring campers away.

The Aldens search for their grandmother's missing necklace.

The children go to stay with their Aunt Jane's friend, Kay, who owns an old motel in Florida. They find that someone is trying to keep it out of business when they decide to help restore it.

The Aldens offer to take care of the animals from the recently closed Greenfield Animal Shelter. They have another mystery in their hands when they discover that most of the animals belong to an old woman who is missing.

The Alden children go on a classic Mississippi steamboat to visit a family friend in Missouri, there they have to uncover who is responsible for the mysterious happenings near the cabin.

The Alden children are trying to raise money for a new hospital wing and make friends with a new girl, Beth, unfortunately both attempts are proving difficult and problematic.