The ghost in the bone-white mask who haunts theankh-morpork opera house was always considered a benign presence -- some would even say lucky -- until he started killing people. The sudden rash of bizarre backstage deaths...The ghost in the bone-white mask who haunts theankh-morpork opera house was always considered a benign presence -- some would even say lucky -- until he started killing people. The sudden rash of bizarre backstage deaths now threatens to mar the operatic debut of country girl perdita x.