When they take their dog, Watch, for obedience training, the Alden children discover that some of the dogs in the class have vanished and decide to try to solve the mystery of their disappearance.

A friendly writer with a metal detector, the mysterious inhabitants of a tower house, and the discovery of a locket in the sand are ingredients for the Aldens' latest mystery.

The four Alden children, aged six to fourteen, volunteer at the new recycling center in town, and help uncover who is breaking in and making a mess each night.

The Alden family rents a houseboat to drift down the river, and encounters a mystery in the little towns along the river, involving a fast black car.

When the Boxcar children help out in a local garden, they dig up one strange thing after another! First, the tomato plants seem to move every day. Find out how that can be.

The Boxcar children must track down an instrument thief in time to save Greenfield's music festival from disaster.

Two brothers take summer jobs at a department store where a series of peculiar events brings them under suspicion.

The Aldens are excited to meet their favorite celebrity--Walter the Cat, who makes the funniest videos on the Internet! And when this celebrity cat inherits a million dollars from his owner, he becomes even more famous! But someone seems to be angry about the will and is stealing things from Walter's house. Is this cat too famous for his own good?

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

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.