House of games3

Overwhelmed by the experience, Margaret is visited by Billy, her patient, but is too distressed to have a session with him. By sheer chance, she spots Billy leaving and sees that his car is the very escape vehicle used during the hotel getaway. Margaret puts the pieces together. She spies on the con men--among whom is the "dead" cop/mark--and confirms that everything was a ruse to swindle her out of $80,000; making love to her, Mike says, was "a small price to pay."
Margaret has a gun (the gun she, ironically, took from Billy in their earlier session). She has overheard when Mike is leaving town and lies in wait for him at the airport. At first she puts on an act, pleading to travel with him with the additional $250,000 she says she has brought. Mike coaxes her into a deserted dock of the airport where they can be alone. When she misspeaks, Mike realizes that Margaret knows the score. He tells her there's nothing she can do about it and turns to leave. Margaret pulls out her gun and dares Mike to beg for his life. He refuses and she shoots him repeatedly until he dies.
Much later, we see that Margaret has gone on with her life, a changed woman, now able to "forgive herself." She shows no sign of guilt or remorse for murdering Mike. She steals a gold lighter out of the purse of another woman in a restaurant and relishes the acquisition.