Peter is a police SWAT officer who shows up to a low-income housing project to enforce martial law. The residents had not turned over their dead to the National Guard and were raided. After Wooley maniacally kills several unarmed residents, most of whom are African American and Latino, Peter guns him down.
After cleaning out the zombified dead in the basement, both Peter and Roger DeMarco are burnt out and want to strike out on their own. They join up with Stephen Adnrews and Fran Parker and use Stephen's helicopter to find a place to hunker down. After stopping for fuel, Stephen nearly inadvertently shoots Peter, causing a temporary rift between the two.
Once they land at a abandoned mall, they clean out the zombies and use a hidden room upstairs as their new home. While Peter and Roger move box trucks to block the entrances to prevent the dead from entering the mall, Stephen learns to shoot with more accuracy. Unfortunately Roger is bitten and within a couple days succumbs to his injuries. Peter watches with hope that Roger will stay dead, but instead he wakes up as a zombie and Peter shoots him to put him out of his misery.
Not long afterward, a roving band of bikers raid the mall. Peter and Stephen monitor the situation but Stephen angrily opens fire on the bikers. Peter and Stephen are then forced to engage in a firefight with the bikers as zombies slowly overtake the mall again. Peter gets away and stays hidden, but Stephen is found and shot in the arm by one of the bikers. Soon he is bitten several times by the zombies and is quickly killed and revived as a zombie.
Knowing where the hidden apartment is, Stephen leads the zombies to Peter and Fran. While Fran climbs to the roof to fly the helicopter somewhere else, Peter, tired of surviving wants to stay behind. He nearly shoots himself in the head with a snub-nosed pistol, changes his mind at the last moment and fights through the zombies to the roof where he and Fran escape with very little fuel left.