Margaret Ford, portrayed by Lindsay Crouse, is a psychiatrist based in Seattle, Washington, who has recently gained acclaim for her book discussing obsessive-compulsive disorder. However, despite her professional success, she feels an emptiness in her life. One day during a therapy session, her patient Billy Hahn, played by Steven Goldstein, expresses serious concerns for his safety, revealing that he is in deep trouble with a criminal known as Mike Mancuso, played by Joe Mantegna. In a desperate moment, he brandishes a gun and threatens suicide. With a combination of compassion and authority, Margaret manages to convince him to hand over the weapon, reassuring him that she will find a way to help.
That evening, driven by curiosity and a need for excitement, Margaret ventures into a dicey establishment known as the House of Games. Here, she confronts Mike, who proposes a risky deal: he will forgive Billy's debt if she can identify a tell by George, portrayed by Ricky Jay, during a back-room poker game. After some initial hesitation, Margaret agrees, keen to immerse herself in this new and thrilling world. During the game, she notices George's nervous habit of playing with his ring whenever he attempts to bluff. She relays this information to Mike, but to her surprise, George wins the hand and demands payment, which Mike can't provide. In a tense turn of events, George brandishes a gun, only for Margaret to discover it is a water pistol. Recognizing that the entire situation is a ruse to con her, she ultimately refuses to pay.
Despite this deception, Margaret is captivated by the thrill of the con and decides to return the following night. She asks Mike to teach her about these games, expressing her desire to write a book on the subject. Though initially skeptical, Mike agrees and begins to teach her some basic tricks. Their relationship takes an intimate turn when they share a night together in a hotel room. During this time, Mike shares a principal belief among con artists: that they should take something small from each victim, reminiscent of a mark's submission. In a moment of curiosity, while Mike is otherwise occupied, Margaret swipes a small pocket knife, mistaking it for belonging to the man who had the room.
When Mike is called away for another con, Margaret insists on joining him, posing as his wife. The setup involves a supposedly lucrative but dangerous game with a businessman portrayed by J.T. Walsh, who unwittingly is participating in a sting operation. As the con unfolds, Margaret realizes the businessman is an undercover cop. Her warning to Mike leads to chaos where a struggle results in the officer accidentally shooting himself. In an adrenaline-fueled escape, they navigate the situation, further complicating matters when they must dispose of a car containing evidence.
Feeling guilty about the entire escapade, Margaret tries to return to her regular life but is haunted by the experiences that transpired. When Billy appears cheerful and drives off in the very car Margaret had stolen, she follows him to a bar and discovers Mike and the gang discussing their plans to swindle her out of her savings. The realization that the pocket knife she took actually belonged to Mike hits her hard, awakening a new sense of betrayal.
In a dramatic confrontation at the airport, under the guise of concern for their safety, Margaret tricks Mike into thinking she wants to run away with him. She reveals her true intention as she brandishes the gun that Billy had threatened her with, forcing Mike to acknowledge his impending doom. Even as he tries to turn the tables on her, she shows no hesitation, resulting in a tragic end for Mike when she shoots him multiple times.
Time passes, and Margaret appears seemingly unscathed by the traumatic events, meeting with Lilia Skala, her friend, over lunch. As they discuss her experiences, Margaret's unrepentant demeanor shines through when she admits, "When you've done something unforgivable, you must forgive yourself, and that's what I've done, and it's done." When her friend steps away, Margaret's thrill for danger resurfaces as she stealthily steals a gold cigarette lighter from another diner, relishing the excitement that comes from living on the edge.
