Case of the Duplicate Key

Sir Alec Prendergast is forced to surrender his mother's pearls to cover gambling debts that were incurred due to swindling by Count Stefani and the Twisted Snake Gang.
Nelson Lee advises Sir Alec to get a loan from Norman Warner, an honest moneylender but unbeknownst to all, his personal secretary, Cynthia Meadows is, in reality, Mrs. Stefani, also a convicted felon, and former member of the gang. She has been jailed-and by Nelson Lee. But she has also reformed; but once a member of the gang...
Count Stefani has lost track of Cynthia but once he finds her, he has ways to steal the Prendergast Pearls held so safely in Norman Warner's safe.