While visiting their cousin's pineapple plantation in Hawaii, the Aldens hear a local legend about a black pearl with a curse on it and investigate mysterious incidents on and around the plantation.

While spending two days touring a zoo to see the baby animals, the four Alden children, aged six to fourteen, help catch an escaped monkey, participate in a photography contest, and investigate a missing camera.

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

The Aldens try to help a visiting Russian gymnast who is surrounded by mysterious people and events and who seems to have a secret.

A series of practical jokes at a restored nineteenth-century farmhouse makes the Aldens wonder if the ghost of its builder is at work.

When Henry's magic teacher, The Amazing Arthur, goes missing right before the Greenfield Magic Shop's annual magic show, Henry and his sibilings look into Arthur's disappearance.

The Boxcar children have dinner at a Chinese restaurant and get a handwritten riddle in a fortune cookie! One riddle leads to another, and the children wonder who is leaving them the cookie clues, and why?

Jessie and Benny are participating in the Great Greenfield Bake-Off, a local baking competition for kids. But ingredients get mixed up during the competition and then the power goes out. Is someone trying to put an end to the contest?

The Aldens are spending a week at Camp Seagull on beautiful Claw Island. But as soon as camp begins, they realize that someone is not playing fair. Everything begins to go wrong for the Aldens — they lose their luggage, Henry misplaces the camp flag, and the campers on the other team use one of Jessie's ideas to score points for themselves. Are some campers so desperate to win the Olympics that they are willing to cheat? The Boxcar Children...

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.