The Boxcar Children help Olivia Chase, the mystery writer, open a new bookstore. When their grandfather buys a bookstore at auction in New Orleans, the Alden children help clean it up and discover that several people seem to be obsessed with the store and its contents.
Someone has stolen the Aldens' boxcar! Can they get it back? The Alden children plan to ride in their boxcar at the Greenfield Founders' Day Parade, but the newly refurbished boxcar is stolen a couple of days before the big event.
When the Hardy Boys eagerly agree to assist their friend Jack Dodd and his father in locating a family treasure, the two young detectives are unaware of the baffling complications that will arise.
Triggered by the disappearance of a brilliant young professor, this mystery takes the Hardy boys first to Kenworthy College, where they find a puzzling message on an examination paper. But then their pal Chet Morton, with his new metal detector, and buddy Biff Hooper, turn up a clue that sends the young detectives on an exciting search in another direction to the honeycomb caves, on the seacoast. A hot tempered hermit who considers the caves his private domain complicates this seacoast mystery and challenges every sleuthing skill Frank and Joe possess.
