Night of the Werewolf — Franklin W. Dixon

THE HARDYS MEET THE MONSTER OF THE MOUNTAINS
A snarling beast is sighted in Bayport, and the boys head into the Adirondacks to investigate a sinister, centuries-old legend. The legend is furry, fanged, and appears only by the light of the full moon. A werewolf is on the loose, and the Hardys are on its trail!

Frank and Joe discover that the case is tied to a series of building-site accidents -- accidents under investigation by their father. Has a werewolf appeared out of the mountains to put the bite on a construction firm? Or is it a man in wolf's clothing? The chilling truth will rise with the full moon, on the shadowy NIGHT OF THE WEREWOLF.