Queen of Diamonds, Knave of Hearts - S1.E16

(intro narration) Night, on a millionaire's estate. Cat climbs to the 2nd story of the mansion, and sneaks into a bedroom; immediately a beautiful woman, who was hiding behind the curtains, holds a small gun to the back of Cat's head. She says facetiously, ""Turn and face your punishment."" Cat quips, ""A punishment fit for a king."" The lady is his long-time friend, the Countess De Laurent; Cat kisses her. The Countess, with her charming foreign accent, tells Cat why she sent for him. She has been married for many years now to a rich American, Robert Lampson. But 3 years ago, she foolishly had a dalliance with that suave knave Gordon Amley, whom she describes as ""handsome and dashing."" When they broke up, Gordon blackmailed her: he threatened to tell her husband about their affair. She gave him a $50,000 diamond necklace, for his silence.

The Countess had an excellently-crafted copy of the diamond necklace made; she is wearing the copy now. Trouble: her husband is having all th