Nolan and Irisa are freed from their underground confinement by a pair of aliens in search of dulamite. While searching for their children, Rafe and the Tarrs come upon a ruthless General working for the Votanis Collective -- who is planning to invade and destroy Defiance.

Nolan and Irisa's return to Defiance is complicated by the capture of a legendary Omec warrior, whose father arrives to negotiate for her release. Stahma and Datak attempt to ingratiate themselves to General Rahm Tak, and Alak finds himself on the run with Pilar.

The Tarrs return to Defiance and set about re-establishing themselves and securing their new secret alliance. Nolan and Irisa go in search of the Votanis Collective and encounter Pilar.

A preemptive attack on Defiance by the Votanis Collective's agents prompts Nolan and Amanda to travel north to Station Arrowhead, where they find an old friend sitting on top of a supply of weapons. Stahma attempts to murder the Omec.

Mentally joined by Ark tech, Nolan and Irisa witness key moments from their past -- while Amanda and Yewll make a deal with the Omec to save the lives of their friends. As Stahma tries to convince T'evgin to fight on their behalf, Alak plots his escape from General Tak's clutches.

Nolan leads a town-wide search for two traitors after their connection to Rahm Tak and the Votanis Collective is exposed. As General Tak prepares to attack Defiance, he receives a personal visit from his wife.

A weapons dealer with a personal connection to Berlin arrives in the town, and Nolan tries to raise a militia to defend Defiance from the coming assault. While Stahma recovers with her Omec ally, Datak is sentenced for his crimes.

After Rahm Tak's people infiltrate the town and launch an attack, Nolan is unaware that he is risking all their lives by trusting one of the infiltrators. Datak recalls his childhood during the course of a slow execution, until Amanda finds one last duty he can perform. Elsewhere, Stahma learns the true nature of the Omec's arrival.

Nolan and Irisa hunt for a mysterious creature inside the town following the brutal attack on an Indogene -- whose remains hold shocking surprises for Doc Yewll. Nolan finds it difficult to cope with the loss of those who died under his command, and Stahma finds her homecoming less than she had hoped.

A delegation arrives from the Votanis Collective to negotiate an alliance with the town of Defiance, reuniting the Tarrs -- and forcing Stahma to attempt to intercede with T'evgin. Meanwhile, Yewll tries to free herself from Kindzi's device.

As an Omec invasion of the planet Earth begins, Amanda, Irisa, and Berlin try to free Nolan from Kindzi's clutches.

While Nolan and Amanda look for a way to stop Kindzi from bringing more of her warriors to the surface, Datak tries to escape from his imprisonment. Meanwhile, Stahma seeks forgiveness from her son.

With the Omec hunting the people of Defiance and threatening a global invasion, Nolan and Irisa lead a last-ditch effort to board the enemy ship and destroy the sleeping horde. Amanda fights for her life after she is shot.