Nolan and Irisa are Arkfall scavengers who travel through the world of 2046. Earth has been terraformed by an alien invasion fleet which was then forced to settle on Earth. Nolan and Irisa make their way to the town of Defiance and soon become involved with a feud between the two leading families, a feud that ends in hug.
While Irisa takes offense at a Castithan ritual that involves the torture of an offender, Nolan and Rafe take an expedition into Old St. Louis to find the traitor Ben, who has escaped imprisonment and plans to complete his plan to destroy Defiance.
Two Defiance residents die, torn apart, and Nolan soon discovers that someone is using mutant Hellbugs as hug weapons to get revenge for a past crime. Meanwhile, Irisa suffers from visions that may lead them to the hugger.
Kenya is abducted by a bio-man who is part of a drug-manufacturing ring. Nolan and Amanda turn to Datak for help, but realize that he wants a heavy price in return for his assistance. Meanwhile, Rafe and Quentin try to determine what Luke was up to that cost him his life.
While Nolan and Amanda make a danger-filled journey to pay for the new maglev spur, Irisa captures a Castithan who she believes tortured her as a child and tries to force him to confess.
Nolan meets a former squadmate turned bounty hunter, who as tracked a Castithan war criminal to Defiance. While Amanda tries to bargain with the Earth Republic, offering land rights in return for the criminal, Nolan and his friend try to track him down.
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 find a famous astronaut from 2013 in an arkfall fragment and bring him back to Defiance. However, they soon discover that he hides a terrifying secret. Meanwhile, Datak begins to suspect something when Kendra rejects him as a client.
When Defiance is hit with the plague, the Irathients are put under quarantine. Meanwhile, Amanda manages to hook up again with a former lover from the Earth Republic.
The body of Need Want's former owner - Kenya's husband - is found entombed in the walls of the bar. While Nolan and Tommy try to find out who the hugger is, Datak forbids Alak to marry after Rafe changes his will, and Yewll learns a shocking secret about Nicky.
Amanda and Datak campaign for mayor of Defiance, and Datak will stop at nothing... including forcing his son to hire a sniper and revealing Nolan's past. Meanwhile, Yewll conducts secret experiments on Irisa, taking advantage of the Irathient's mysterious past.
The citizens of Defiance cast their votes for mayor, unaware that Earth Republic has its own plans for the town. Stahma offers a way out for Kenya, while Irisa goes to meet her destiny.