First valuable antique weather vanes are stolen in Pennsylvania Dutch Country and Frank and Joe are hired to catch the thieves. Meanwhile, their father is asked to find a missing Navy employee and a top-secret government document. What is the connection between the missing weather vanes and the Pentagon spy? The final chapters of this thrilling mystery uncover a stunning revelation!

When a man selling leather goods door-to-door steals the key to their detective father’s file cabinet, Frank and Joe Hardy set out to track him down. An odd mark on a key case which the man sold to their mother leads the teenage sleuths to an Indian village, whose chiefs begs them to help him find valuable tribal possessions and the deed for his land. How Frank and Joe find the missing deed and Ramapan treasures, how they prevent the phony leather-goods salesman from carrying out a ruthless scheme and how they help their father solve the top-secret case he is working on for the U.S. government makes exciting reading for all fans of the Hardy boys.

When an ancient stone idol disappears, the Hardy Boys are off on another fast-paced adventure. It's a mystery that takes the boys from a primitive village in the Andes Mountains to Antarctica and finally to Easter Island. By using their fine investigative skills, the Hardy Boys find that the mystery of the stone idol is not what it seems!

When the Hardy Boys take a winter vacation in Jamaica, Joe finds an ancient bronze death mask washed up near their beach house during a violent storm. Helping the Hardys and their friends in this bizarre mystery is William, a Jamaican boy, who flies to New York with startling news, only to be intercepted and held for ransom—the death mask! Frank and Joe must rescue William, plunge into their father’s airline-ticket theft case, and fly into a maze of danger in Africa.

Once again Frank and Joe Hardy take on a puzzling case when their famous detective father asks the boys to assist him in tracking down a notorious jewel thief and his accomplices. The trail leads to the outskirts of the Hardys’ home town and to a weirdly guarded mansion on the old Perth estate. With their pal Chet Morton, the brothers must tackle the mystery of the mansion heir’s sudden death. A disappearing floor, a huge, savage-looking, hound, a galloping ghost, and a college professor’s startling invention are just a few of the strange elements that complicate the boys’ efforts to solve both mysteries.

A dying criminal confesses that his loot has been stored "in the tower." Both towers of the looted mansion are searched in vain. It remains for the Hardy boys to make an astonishing discovery that clears up the mystery and clears the name of a friend’s father.

A long-distance telephone call from Chet Morton’s uncle summons Frank and Joe Hardy and their staunch pal Chet to a summer art school, located near old Fort Senandaga which is reputed to be inhabited by a ghost. The young detectives’ assignment: recover two famous oil paintings stolen from the valuable Prisoner-Painter collection owned by Jefferson Davenport. Mr. Davenport reveals that one of the famous pictures contains a clue to the hiding place of a priceless gold chain. Vicious threats and deadly traps beset Frank, Joe, and Chet as they search for clues to the stolen paintings and the gold treasure – a search that is complicated by the stormy feud between an Englishman and a Frenchman over the military history of the ancient fort.