The Secret of the Old Mill

In the third installment of The Hardy Boys series, Frank and Joe embark on a daring investigation into counterfeit money circulating in Bayport. Their quest leads them to an old, mysterious mill filled with secret passages and strange noises, where they soon discover they are being watched by someone intent on keeping the truth hidden. As they delve deeper into the case, the brothers face dangerous secrets and must work quickly to uncover the truth before they are caught in a deadly trap.