It's just not William Foster's (Michael Douglas) day. Laid off from his defense job, Foster gets stuck in the middle of the mother of all traffic jams.
Desirous of attending his daughter's birthday party at the home of his ex-wife (Barbara Hershey), Foster abandons his car and begins walking, encountering one urban humiliation after another (the Korean shopkeeper who obstinately refuses to give change is the worst of the batch).
He also slowly unravels mentally, finally snapping at a fast-food restaurant that refuses to serve him breakfast because it's too late. Running amok with an arsenal of weapons at the ready, Foster -- also known as D-FENS because of his vanity license plate -- rapidly becomes a source of terror to some, a folk hero to others.
It's up to reluctant cop Prendergast (Robert Duvall), on the eve of his retirement, to bring D-FENS down.