The arrival of the mysterious Nolan and his charge Irisa to the town of Defiance marks a threat to the fragile peace that exists between the residents in the premiere of this futuristic drama, which is set in the year 2046, more than 30 years following a war between humans and aliens that left Earth forever changed.Nolan sticks around to help Defiance defend itself from an attack; and under Mayor Amanda Rosewater's leadership, the aliens and humans of the town set their differences aside long enough to rally against a Volge threat.
A killer is pursued; at the same time, Nolan and Datak come to blows over an ancient ritual.
Irisa is forced to confront a disturbing power; at the same time, Defiance is invaded by a swarm of menacing Hellbugs.
Kenya is kidnapped; Rafe moves a step closer to learning the truth about his son's death.
Nolan and Amanda find themselves in danger as they attempt to transport a prisoner out of town; and Irisa's mood grows dark after a run-in with the man she believes tortured her as a child.
An old war buddy catches up with Nolan at the same time a Castithan criminal with a history of violence enters the picture.
Interesting relationships develop when the residents of Defiance are forced to stay indoors as a threatening Razor Rain storm approaches. Meanwhile, visions lead Irisa to the Spirit Riders and Sukar, who has fallen under the influence of a strange and mysterious force.
Nolan and Tommy encounter an American astronaut who has been in hypersleep for several decades.
The Irathients are quarantined in the mines after Defiance is struck by a mysterious plague; and Amanda reconnects with an old flame from the Earth Republic.
The body of a prominent businessman who disappeared nearly six years ago is discovered hidden in the walls of NeedWant, prompting an investigation by Nolan and Tommy that exposes many of the secrets held by the people of Defiance. It also causes unrest on the eve of Alak and Christie's wedding.
Nolan's involvement in an accident on the eve of the election has the town questioning his role as lawman and Amanda's credentials as potential mayor.
Amanda is locked in a bitter power struggle with Datak as the citizens of Defiance cast their votes for mayor. At the same time, Nolan is violently confronted by his past; and Irisa must decide whether or not to accept her destiny.
