The Aldens investigate when the new coach of their community basketball league has her Most Valuable Player trophy stolen.

While staying at the Crooked House, the family home of their housekeeper Mrs. McGregor, the Aldens try to solve a riddle that will lead them to a hidden treasure.

While visiting a friend in New York City, the Aldens investigate the theft of a valuable diamond.

The Aldens investigate a mystery involving a legendary mining expedition to the gold fields of Alaska.

Benny anticipates making friends with the new kid down the street, but when he finds out that she's a girl, he is very disappointed.

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.

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

The Aldens help a farmer whose honeybees have stopped producing honey and discover a sabotage scheme.

The Aldens visit Grandfather's friend at the Ogopogo Retreat and aided by puzzling clues, embark on a treasure hunt to prevent the retreat from being sold.