The adventures of the four Alden children as they spend a summer vacation on their very own island, purchased by Grandfather's father years ago.

The Boxcar Children are spending the summer in an enormous New England farmhouse. There's an old woodshed near the house that holds a surprising secret--a secret that dates from the Revolutionary War. Suddenly their summer becomes an adventure.

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.

Because they do not want to be separated, four orphaned children run away and live in an old abandoned boxcar

While visiting Lake Lucille in the Adirondack Mountains, the Aldens hear stories about a monster in the lake and then encounter evidence that it may be real.

When a professional hockey player comes to Greenfield with plans to build an ice skating rink, the Alden children suspect that someone in town wants to stop the project.

When the Alden children go camping on Blizzard Mountain, a place said to be inhabited by a ghost looking for buried treasure, they begin to think someone or something is trying to scare them off.

The Aldens' dog, Watch, comes across a mysterious box with a note inside, a box that is part of a game called Geocaching. Henry, Jessie, Violet, and Benny join the game but soon suspect one of the members of the geocaching club is a thief.

The Aldens visit the shore in New Jersey and help out at an amusement pier that is rumored to be unsafe.