Chandler faces his powerful enemy in a final showdown. Kara joins someone that can help with her mission.

Chandler returns to America to find out what has really been happening.

With Chandler and Tex caught in a dangerous situation, Slattery has to step into the role as commanding officer. Torn between a mission with the fate of the world at stake and a Captain (and friend) in danger, Slattery has to find a way to get his people back without losing the most important asset: the vaccine prototype.

Rachel and Chandler ask for six volunteers to participate in human trials of her vaccine, but the tests could be a living hell as the virus and the vaccine do battle inside their bodies. Meanwhile back in the States, Chandler’s wife and father are doing everything they can to keep their family alive.

With their mission now fully dedicated to spreading the cure, Nathan James puts a call out to civilians to meet at pre-selected ports across the country.

Chandler gets a lead that could help answer threatening questions. Kara does some digging in the White House.

Chandler finds himself making a difficult decision when an order comes in from the White House.

With a devastating hostage situation occurring back home, Chandler must devise the perfect plan to avoid losing everything.

The Nathan James must evade an overwhelming threat. A revelation in St. Louis puts President Michener in a terrible position.

After a message is broadcast implicating the Navy in a devastating disaster, Chandler looks to infiltrate the network and regain the trust of the American people.

After the horrifying revelations and reversals of fortune in Baltimore, Chandler and his fractured team join forces with an underground resistance in an attempt to defeat Amy Granderson. With doses of the cure running low, Rachel tries to do some good for the sick while remaining a prisoner at Avocet. Meanwhile, Slattery and the crew of Nathan James are in a race against time to save an injured Dr. Tophet and regain control of their ship.

Chandler confronts his enemy — and his personal demons — in a final showdown, with the fate of humanity on the line.

Chandler's mission comes to a head as he prepares the final part of his plan. President Michener ponders the fate of his presidency.

Chandler's mission becomes complicated as his position is worsened. President Michener faces pressure from the regional leaders.

Chandler tracks a new threat to Northern Florida. Meanwhile, Rachel comes across a secret formula that her mentor, Dr. Hunter, had been perfecting.

Chandler's leadership is put to the test when the ship's propulsion system is in danger of breaking down, the crew becomes overworked and exhausted, and Dr. Scott could potentially lose all of her research on the virus.

As Nathan James and her allies attempt to prevent the enemy moving north, Chandler's haunting visions manifest into reality.

Sixteen months after thwarting the coup in America, Nathan James must face yet another global disaster. The question remains, where in the world is Tom Chandler?

The search continues with a reconnaissance mission but things turn violent when an old foe resurfaces.

With Rachel close to a breakthrough on her vaccine, she, Chandler and XO Slattery lead a small team into the jungles of Nicaragua on a mission to find monkeys for her vaccine trials. While there, they find much more than they bargained for when they run across a former drug kingpin who will stop at nothing to maintain his stranglehold on his oppressed society. Chandler and his men find themselves in a huge moral dilemma over whether to eliminate this menace or take what they need and continue on with their mission.

Rachel is hard at work on a new, more efficient version of the cure while Alisha decodes a message found on a recovered cell phone.

Nathan James must seek the aid of a prominent rebel leader in order to create a staging area before mounting an invasion of their own.

Having lost their only lead, the crew of Nathan James continues their search for an item that could save the world. Chandler immerses himself in a mission for revenge.

An undercover mission in the land of the dead leads to disturbing revelations about Dr. Vellek's sinister plans.

With nations being rapidly occupied, Chandler tries his hand at diplomacy to unite two hostile countries so they can fight a common enemy.

Nathan James's crew searches for a precious item leading them to a strange place of opulence and violence where they cross paths with a most unexpected ally.

Still trying to piece together Dr. Hunter's lost formula, Rachel grapples with her sworn enemy's presence on board the Nathan James.

Chandler and crew race to find answers in an Asian Dodge City. Slattery begins to unravel the truth about his troubling predicament.