I have this book in a Swedish book series translated into Swedis.
B. Wahlströms Ungdomsböcker.
Green edges on books for boys and red edges for girl.
Will soon start adding them to this world.
Summary
While searching for the guard end of a broken saber that will solve one mystery, the Hardy brothers become involved with a gang of bank robbers.
LC Subjects
Hardy Boys (Fictitious characters)--Juvenile fiction.
Private investigators--United States--Juvenile fiction.