On the Aldens' train journey they find that Caboose Number 777 has a secret, and they discover clues about its past at every stop.

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.

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 children, snowbound in a vacation cabin, discover adventure in surrounding wild life, three children they find in the snow, and a search for a lost recipe.