Dan Gallagher is a New York City corporate lawyer with a beautiful wife, Beth, and a 6 year-old daughter named Ellen who spends a weekend with a book editor, Alex Forrest. As far as Dan is concerned, it's a one time thing but Alex has something more in mind, as she amply demonstrates even before the weekend is over. When he makes it clear that there is no future for them, Alex begins to seek him out, whether calling him constantly calling him at home or at work and even visiting his apartment, which is up for sale, and meeting Beth. Alex's obsession knows no bounds and she becomes increasingly violent, putting Dan's life - and that of his family's - in danger.
