Set in the near future, seven different alien species known collectively as Votans have come to Earth seeking a new home after their star system was destroyed. However, upon reaching Earth they found that they were not welcome. The Votans waited in orbit for six years as prolonged negotiations with Earth governments for settlement on the planet ultimately proved fruitless. With supplies on their ships running low, eventually in desperation the Votans began a war with humans to force the issue and make Earth their new home. During the war, Votan ships shot down by human militaries accidentally released terraformer technology, which made haphazard and radical changes to the biosphere and even the geology of Earth, making the planet dangerous to both humans and the aliens.
The earth was scorched, chasms opened in the ground, and the surface of the planet was covered with dust and debris. After decades of war, both sides had fought to the point of mutual exhaustion, and a ceasefire was declared. Few organized governments remained for either the humans or the aliens, and both sides factionalized as their members began looking out for themselves. In several areas, local human and Votan militias began to band together when they realized that they had to cooperate if they hoped to survive on this new almost alien planet.
Jeb Nolan was only ten years old when the Votans arrived and he served in the military during the war. With the war now over, he returns to his hometown of St. Louis to find that its is no longer the city he left; it is little more than a refugee camp renamed "Defiance". Deciding that his services are needed, Jeb takes up a position as the Chief Lawkeeper in Defiance, so he can protect the town from dangerous clashes between humans and aliens, military scavengers and other dangerous visitors who occasionally enter the town.