Henry, Jessie, Violet, and Benny used to live alone in a boxcar. Now they have a home with their grandfather, and they're going to visit his old school with him!   The Aldens are spending a weekend at Goldwin University for Grandfather's college reunion. The Alden children are immediately fascinated by the tall, mysterious clock tower that overshadowed the campus. They soon learn the valuable secret from the past lies hidden somewhere at the old school—and they think the clock tower might hold the key to discovering it! But there are strange lights coming form the clock tower at night. Is the tower haunted by ghosts of the past? Or is someone else searching for the secret of Goldwin University? The Boxcar Children are convinced that someone at the school is not what he or she seems—and they are determined to find out who it is!