The Legions of Ammak

Mannering is asked by an eccentric millionaire to witness him purchase The Legions of Ammrak, a golden necklace that contains seven perfectly matched black pearls. The Baron identifies that they are genuine but David Marlowe notices that the seller, King Ibrahim, is wearing the wrong school tie. When Mannering realises that he's being duped, he has to recover both the money and the necklace.