8 Hardcover Hardy Boy books, 1-10#
Tower Treasure, House on Cliff, Secret of Old Mill, Missing Chums, Hunting for Hidden Gold, Shore Road Mystery, Secret of Caves, Mystery of Cabin Island, Great Airport Mystery, What Happened at Midnight
1995
First Published
1
Number of Pages
Determined to learn the secret of the old mill, Frank and Joe employ a clever ruse to gain entrance and become trapped. There they unravel two mysteries, one involving a counterfeiting case and the other, a national security case their father is working on.
