Bobby Davis (Jake Webber) is a middle-aged salesman from Detroit who has come out west with some work colleagues for a two-week business seminar. His fellow salesman Jerry (David Thornton) tells Bobby about the "100 mile rule," which states that if you are more than 100 miles from home, you can cheat on your spouse without feeling guilty. Bobby is a happily married man and he has no intention of cheating on his wife, but then one evening he goes for a jog to relieve some tension and encounters a sexy waitress named Monica (Maria Bello). He's drawn to her despite himself, but their one night together will turn Bobby's entire life upside down, threatening everything he cares about.