approx. 3 hours
Determined to learn the secret of the old mill, Frank and Joe employ a clever use 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.
Franklin W. Dixon (Author)
Franklin W. Dixon is the pen name for Edward L. Stratemeyer who originally began the series. It is not proven, but said, that his daughters updated and continued the series after their father's death in 1930.