The Alden children start out on a one-day mountain climbing excursion that becomes very exciting. One warm night four children stood in front of a bakery. No one knew them. No one knew where they had come from. Henry, Jessie, Violet, and Benny used to live alone in a boxcar. Now they have a home with their grandfather and are spending the summer mountain climbing in New England. A dangerous rockslide, a mountain cave, a secret treasure -- there are many adventures in store for the Boxcar Children in the Mountain Top Mystery. - Publisher.