Law & Order: Criminal Intent (2001) : 8x13

When poker genius Josh Snow loses $80,000 in a card game, backer and bookie Lou Cardinale forces him into collections to work off the losses. Lou gives him a .38 and a box of blanks to extract gambling debts, and sends along his mistress, Angela, to keep an eye on the money. Detectives Goren and Eames enter an elaborate game where they must join in the play, or be played.