A laid-off defense worker is on a path of violence and self destruction, and now an LAPD detective, only hours away from retirement, must find him and stop his vigilante acts.

On the day of his daughter's birthday, William "D-Fens" Foster is trying to get to his estranged ex-wife's (Barbara Hershey) house to see his daughter. He has a breakdown and leaves his car in a traffic jam in Los Angeles and decides to walk. Along the way he stops at a convenience store and tries to get some change for a phone call but the owner, Mister Lee, does not give him change. This destabilizes William who then breaks apart the shop with a baseball bat and goes to an isolated place to drink a coke. Two gangsters threaten him and he reacts by hitting them with the bat. D-FENS continues walking and stops at a phone booth.

The gangsters hunt him down with their gang and shoot at him but crash their car. William goes nuts and takes their gym bag with weapons proceeding in his journey of rage against injustice. Meanwhile Sergeant Martin Prendergast, who is working on his last day before retirement, is following the wave of crimes and believes that the same man is responsible but the other detectives do not pay attention to him.