The Hardy Brothers Detective Stories is a classic, original series of stories about brother detectives. It was published from 1927 to 1979. AST Publishing publishes this series under the title “The Hardy Brothers Detectives.”

A new exciting mystery awaits Frank and Joe Hardy when they help a stranger who has been involved in an accident. The man introduces himself as John Mad, the owner of the estate. After he leaves, Frank finds a strange key, apparently belonging to Mad. Trying to get him back, the brothers learn that John Mad died five years ago! Their surprise grows when the boys discover that the intricately carved doors in the abandoned mansion have neither handles nor keyholes. At the same time, the boys help their father in searching for a gang of criminals who are robbing warehouses of television and stereo equipment.