La secta de los misteriosos

Also known as Die sekte der Geheimnisvollen

Barcelona, early twentieth century. While a trio of masked burglars and their minions search for an ancient Moorish treasure that can only be located when the two parts of an ornamental chain are connected, Inspector Hernández and his faithful assistant Carlos follow the dreadful crime path they walk by. (Only the German cut of the three original Spanish episodes has survived.)