Dan Gallagher (Michael Douglas), an attorney, and his wife Beth (Anne Archer) attend a social function in New York City. They meet up with their friends, Jimmy (Stuart Pankin) and his wife Hildy (Ellen Foley), and mingle. Jimmy notices an attractive blonde, Alex Forrest (Glenn Close), undressing her with his eyes. She gives him an icy look and walks away.
After bumping into Alex at the bar, Dan tries a more gentle approach; casual, small talk while sipping champagne. They laugh off Alex's cold rejection of Jimmy and exchange names. After establishing he is married, (Alex sees Beth waving to Dan), Dan shoots Alex a sexy glance before he leaves. The seed for a potential affair has been planted. ()
LOCK IN (End of Act 1)
Beth visits her parents, taking her child Ellen (Ellen Hamilton Latzen) with her and leaving Dan by himself for the weekend. Later that day, Dan discusses a case with his colleagues at his office where he crosses paths with Alex again. The two have dinner in a fancy restaurant. Trust is built and, when the opportunity presents itself, Dan and Alex engage in a wild, passionate love affair. ()
FIRST CULMINATION (Midpoint)
Alex tries to squeeze herself back into Dan's life, harassing him with phone calls to his office. Dan avoids her, until she wakes him with a call at his home in the middle of the night. Alex and Dan meet at a New York subway station where she tells him she's pregnant. ()
MAIN CULMINATION (End of Act 2)
After Beth discovers her daughter's dead rabbit cooking on the kitchen stove, Dan comes clean. He admits his affair with Alex to his wife. When Beth presses him, Dan confesses that Alex is pregnant. ()
THIRD ACT TWIST
As she prepares to take a bath, Beth wipes steam off a mirror, only to reveal Alex standing behind her, holding a kitchen knife. In the ensuing fight between Beth and Alex, Dan hears his wife's cries for help and rushes upstairs. He viciously attacks Alex and drowns her in the bathtub.
But Alex is not dead. She emerges from the water, plunging towards Dan before Beth fires a bullet into Alex's chest, killing her and Dan's unborn child. ()