“The Secret of the Old Mill” is the third installment in the “Hardy Boys” series of mystery stories. Written by Canadian author Charles Leslie McFarlane and published under the pen name, Franklin W. Dixon, in 1927, “The Secret of the Old Mill” ranks as one of the best books in the series. In this thrilling installment, readers find the Hardy brothers, Joe and Frank, investigating the mysterious appearance of counterfeit money in their small town of Bayport when one of their friends discovers that he has been given the fake bills. The brothers are soon threatened by anonymous warnings telling them to drop the case but they refuse to be dissuaded. Soon their investigation leads them to an abandoned old mill, where they find a secret passage and the answer to this dangerous mystery. “The Secret of the Old Mill” is an exciting and suspenseful tale sure to thrill fans of the resourceful Hardy brothers. Presented here is the original version of “The Secret of the Old Mill”.