Married man Charles Schine (Clive Owen) meets Lucinda Harris (Jennifer Aniston),ia high powered businesswoman, onia commuter train one morning. An innocent conversation leadsito an evening drink.

Before either one can stop it, their aroused passions leaditoia sizzling one-night stand. Suddenlyia stranger explodes into their world, threateningito expose their secret, andilures them intoia terrifying game with more surprises than they saw coming.