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

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 helping run Jerry Taylor's general store, the Alden children investigate his mysterious employee Nancy.

Someone is trying to put Aunt Jane's motel out of business, but the Alden children aren't going to let that happen.

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

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.

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

While visiting the seaport town of Ragged Cove, Massachusetts, the Alden children find the ship's log of the Flying Cloud, shipwrecked in 1869, supposedly during a mutiny.

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.