Plot

A stranger mentors a young, troubled Reno gambler.

John has lost all his money. He sits outside a diner in the desert when Sydney happens along, buys him coffee, then takes him to Reno and shows him how to get a free room without losing much money. Under Sydney's fatherly tutelage, John becomes a successful small-time professional gambler, and all is well, until he falls for Clementine, a cocktail waitress and sometimes hooker.—Jon Reeves <jreeves@imdb.com>

Sydney is a veteran gambler in his sixties who still spends his time at the casinos. When he meets John, a loser with no money at all, he sees him as a son and tries to help him. He takes care of him and teaches him all the tricks of his work. He also helps him to make a relationship with Clementine, a young girl who works at the casino as a waitress. John doesn't seem to be bothered by the fact that Clementine is also a hooker, but soon something happens that turns their lives upside down.—Chris Makrozahopoulos <makzax@hotmail.com>

John (John C. Reilly) is a down-and-out gambler who lost all his money gambling at Las Vegas. The first time he appears, he's sitting outside a diner and Sydney (Philip Baker Hall) sees him. Sydney offers to help John learn how to navigate the Las Vegas world. This means placing small bets, establishing himself and getting 'comped' for a room at the casino.

Life at the casino is good for John and Sydney. While staying there, they meet two people who become important to the film: Jimmy (Samuel L. Jackson) is a small-time player in the Las Vegas scene and Clementine (Gwyneth Paltrow), a full-time cocktail waitress and a part-time hooker. Sydney takes Clementine under his wing just like he did John.

John and Clementine get married and when Clementine has sex with a visitor to Vegas (F. William Parker) who refuses to pay, John angrily kidnaps and attacks him. John telephones Sydney to come over and help straighten things out. When Sydney gets to the motel where John and Clementine are holding the hostage, Sydney removes evidence that they were there and tells the newlyweds to go away.

They leave headed for Niagara Falls. Jimmy then enters and tries to blackmail Sydney with the knowledge that Sydney killed John's father. It seems that Sydney meeting and helping John wasn't an accident after all.

The title comes from lingo used by gamblers while playing Craps. Rolling a seven with two dice is the most likely result. Eight and Six are the second most frequently rolled totals with two dice. In order to increase the payout for these number combinations, a bet can be made that requires a pair of threes for a 'Hard Six' or a pair of fours for a 'Hard Eight'. Early in the film Philip Seymour Hoffman loses while playing for a 'Hard Eight'. Later in the film Jimmy gambles for a 'Hard Eight' and wins.

At the end of the film Jimmy's luck runs out. While celebrating his 'Hard Eight' victory, Sydney ties up the loose ends by killing Jimmy.