In the year 2046, it's a new Earth - with new rules. Over thirty years after various alien races arrived on Earth, the landscape is completely altered, terraformed nearly beyond recognition. To the town of Defiance, on what used to be St. Louis, comes the mysterious Nolan (Grant Bowler) and his charge, Irisa (Stephanie Leonidas). As they settle into town - overseen by the mayor, Amanda Rosewater (Julie Benz) and filled with residents like the powerful Rafe McCawley (Graham Greene), enterprising lounge owner Kenya (Mia Kirshner) and the ambitious, alien Tarrs (Tony Curran and Jaime Murray) - events begin to unfold that threaten the fragile peace this border town has fought for.
Set on a future Earth, Defiance introduces players and viewers to a world where humans and aliens live together on a planet ravaged by decades of war and transformed by alien terra-forming machines. It centers on Jeb Nolan, the law-keeper in a bustling frontier boomtown that is one of the new world's few oasis of civility and inclusion. Nolan is a former Marine who fought in the alien conflict and suffered the loss of his wife and child in the war. The trauma transformed him into a lone wanderer in the wilds of this new and dangerous world.
- The series is set in the near future, where aliens known collectively as Votans have come to Earth seeking a new home after their solar system was destroyed. However, when they reached Earth, they discovered despite a prolonged negotiation with the government on Earth, they were not welcome. Rather than turn away, they began a war with the humans as they are determined to make Earth their new home. During the war, the Votans dropped terraformers on the planet and transformed the surface; scorching the earth, opening chasms in the ground and covering the surface of the planet in dust and debris. After decades of war, a ceasefire is declared when both sides realise they must focus on survival on this new almost alien planet. The series largely revolves around the character of Jeb Nolan. Jeb 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 it's is no longer the city he left; it is little more than refugee camp. Deciding 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, aliens, military scavengers and other dangerous visitors who occasionally enter the town