"The 'Man with Half a Face' owns an island home, and underneath he has arraigned great caverns "of concrete with glass roofs where he stores his ill-gotten gains and keeps a tame submarine to sink bullion ships as they approach the shores of England. He is a criminal in a very big way, and untroubled by any scruples. Death is every form is at his command, from secret poisons to mass murder by gas, and Colonel Royston and Castle from Scotland Yard risk their lives many times before they succeed in unmasking the bad lad."