Philip Seymour Hoffman has cornered the market on playing timid, badly dressed, mouth-breathing sad sacks (''25th Hour,'' ''Happiness''), yet it's easy to forget that what gives his loser characters such singular life is their deep-down obsessional fervor. It's as if his pudgy body and slovenly clothes were insulation that concealed a tiny, raging gasoline fire in the pit of his stomach. In Owning Mahowny, Hoffman plays a fubsy assistant bank manager in gray-skied Toronto who is also a closet gambler (he keeps jetting off to Atlantic City to lose bigger and bigger sums of money). Hunched over the blackjack table, Hoffman shows no expression but a beady glimmer of excitement and fear. He plays Dan Mahowny's addiction to instant money as something dirty and private and, at the same time, soul-quickening.
In hock, Mahowny starts to dip into the loan files of his bank clients, to the tune of thousands and then millions. He keeps enlarging the hole he's in, yet that's the trigger for his high: He's a lousy gambler -- a chump -- who creates a situation in which hitting the great run of his dreams will redeem his existence. Set in the early '80s, ''Owning Mahowny'' is based on a true story, and the director, Richard Kwietniowski, stages it as a real-life fairy tale riddled with pinpricks of dread. As Mahowny's girlfriend, Minnie Driver is as winsomely appealing as she is, in Shelley Long drag, utterly unrecognizable.