"Henry, Jessie, Violet, and Benny have a fun new job: fixing up an old castle! The spooky old place will be turned into a museum, but first the Aldens must figure out why so many odd things keep happening. Keys go missing, strange music comes from a deserted tower, and soon the Boxcar Children discover the castle has a amazing secret!" -- p.[4] of cover.

"Gertrude Chandler Warrner's The boxcar children."