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.