By Franklin W. Dixon
Frank and Joe Hardy are made up our minds to convey to justice the vicious criminals who abducted their detective father whereas he was once research sabotage of a road-building undertaking within the Kentucky desolate tract. After Mr. Hardy’s get away, the 2 younger sleuths are spurred into motion while he mumbles the note “Felix” and so they find a file of a infamous ex-convict was once stolen from his documents. the path leads them to manhattan urban yet ends by surprise in a cemetery! With the hot clue of a spiral image the men head to Kentucky as a part of a street building staff to trace down the abductors and saboteurs.