The Haunted Fort is Volume 44 in the original The Hardy Boys book series published by Grosset & Dunlap. The story starts with the boys' friend Chet Morton who is going off to attend a summer art school in New England. He calls on the Hardy Boys to solve the mystery of the theft of two valuable oil paintings in the area of Millwood. The Hardy Boys accept the proposal and go along with Chet to the Millwood school. In the school, they meet a millionaire - Mr. Davenport, who owns a fort, known as less