After a good-hearted outlaw turns himself in for a fatal accident, the guilt-ridden Sam Phoenix is ready to be hanged when an unexpected pardon arrives in the form of an alien-insect invasion.

As the bloody killing spree begins, Sam and a small number of survivors are forced to take refuge in a nearby church. Realizing they are going to need a lot more than a prayer and a pistol to survive this nightmare, the small community enters a showdown where only one species will make it out alive.