Henry, Jessie, Vioet and Benny Alden are brothers and sisters - and tehy're orphans. The only way they can stay together is to make it on their own. One night, during a storm, the children find an old red boxcar that keeps them warm and safe. They decide to make it their home.

A family starts out on a one-day mountain climbing excursion that becomes very exciting. In fact, it becomes an adventure for the former "boxcar" family. They unearth some mysteries and have a fine time in the process.

Traveling with Dr. Iris Perez to Iceland to investigate activities attributed to local superstitions, the Alden siblings learn the legend of the mischievous huldufolk elves before uncovering clues that offer scientific insights into the strange phenomena.

Four orphaned and homeless siblings happen upon an abandoned boxcar, which, with a little creativity and hard work, they gradually furnish with all the comforts of home. Fearful that they will be sent to live with the reputedly cruel grandfather they have never met, the children keep their new home a secret--until a serious illness forces them to reveal themselves in order to save young Violet.