Julian Noble (PIERCE BROSNAN) is a professional hitman who, despite being older and a bit pricey, is extremely proficient at what he does. Yet, of recent, he's started having some work-related problems that appear to stem from a midlife crisis and/or nervous breakdown. They come to a head while on location in Mexico on his birthday when he realizes he has no friends and no place to call home.
Accordingly, and while intoxicated, he latches onto businessman Danny Wright (GREG KINNEAR) who's left his wife Bean (HOPE DAVIS) back in Denver for several days while he and his partner try to land a lucrative deal with a Mexican firm. Having lost both his job and child (the latter in a bus accident), Danny's been down on his luck for several years and hopes this potential deal might be the thing to break him out of that rut.
The two strike up a conversation at the bar that ends up going bad, but when Danny must stay in town a bit longer to try to close the deal, Julian sees his chance to apologize and perhaps form some sort of friendship. Danny is initially reluctant, but once he learns what Julian does and actually believes it, he becomes somewhat morbidly fascinated with the man and his work.
Yet, as Julian's personal problems continue to affect his work, he finds himself in an awkward situation with his immediate handler, Mr. Randy (PHILIP BAKER HALL), who isn't pleased that his assassin is turning soft. Soon, the hitman is a target and Danny must decide what, if anything, he can or should do to help his new friend.