Four orphans take shelter in an old boxcar during a storm, and, determined to make it their own, they turn it into a safe, cozy home.

The Aldens are helping out at a rescue ranch for horses. Jessie's favorite is a beautiful horse named Dragon. When Dragon and other horses disappear from the pasture, the Boxcar children must saddle up for a mystery. What's happening to the horses at the Dare To Dream Ranch?

"One day in the park, the Aldens' dog, Watch, comes across a mysterious box with a note inside. 'Congratulations!' the note says. 'You've found it!' The box is part of a game called Geocaching. Soon, Henry, Jessie, Violet, and Benny are searching all over town for hidden boxes and making friends with other kids in the geocaching club. But is one of the club members a thief?" -- p. [4] of cover.

The Aldens discover there's nothing more fun than a drive-in movie. But pranks and other odd things are happening at the Diamond Drive-In, and late at night, a ghost is seen walking around the empty lot. Is the old theater really haunted?

Taking a shortcut through the Greenfield Cemetery, the Aldens stumble across a local superstition which maintains that visitors are required to leave gifts or suffer the wrath of a malevolent ghost, a suspicious tradition that prompts the children to expose the truth.

When the Alden children accompany their grandfather on a trip to Seattle, they discover clues throughout the city, seemingly planted just for them.