A successful New York attorney, seemingly content in his marriage, has a weekend affair while his wife and daughter are out of town. The woman he spends the night with, an alluring editor for a publishing company, appears to understand the fleeting nature of their encounter at first. However, what begins as a seemingly simple and passionate indiscretion soon turns into a much more complicated and disturbing reality when she refuses to allow their brief connection to end with the weekend.

As the attorney attempts to resume his normal life and return to his familial routine, his one-time lover begins to intrude on his day-to-day existence, first with calls and unexpected visits, and eventually with progressively unsettling behavior. Despite his efforts to make it clear that the affair was a one-time mistake that he regrets, she will not be dismissed or ignored. Her behavior escalates from needy persistence to an obsessive and dangerous fixation, putting at risk everything he holds dear.