The crew of Nathan James discovers that hospital ship USNS Solace was sent to sea to wait for Dr. Scott's cure. Captain Chandler sees an opportunity to add another ship to their fleet while Rachel is eager to find a lab better equipped to replicate the vaccine. When Solace fails to respond to radio communications, Chandler and his team board the ship...and come face-to-face with an unexpected enemy.

With a small group of survivors from Solace in tow, Chandler and his crew square off against an enemy of the most dangerous kind - a nuclear-powered submarine led by rogue British naval officers, Sean and Ned Ramsey. XO Slattery interrogates a captured mercenary from the hospital ship in an effort to extract information on the sub and its mission. As Nathan James engages in a perilous game of cat-and- mouse, the truth about the mercenary sub unfolds.

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 finds itself trapped between the submarine and civilian blockades.

Chandler must find a way to return to his old crew and investigate a dangerous new foe.

Chandler must confront his suspected new foe. Slattery learns more about the supposed virus mutation. Pressure mounts on President Michener as the situation worsens.

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

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

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

America copes with tragedy while Chandler further investigates the possible virus mutation.

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.

The fight for America comes to an end; Chandler faces a challenge that could change his life forever.

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.

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.

Nathan James is diverted from their mission when they receive a suspicious distress call from a fishing trawler.

With an enormous storm on the horizon, Nathan James must navigate an equally terrifying threat in order to make it to safety.

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

The crew of Nathan James faces a threat that will test the limits of their Naval tactics and strategies.

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

Three years after overcoming the global famine, the United States Navy is ready to unveil its first fully functional fleet since the Red Flu pandemic, but a new type of threat may mean the next world war.

Thrust back to World War II era military technology, Nathan James must think fast to survive a fight with limited weapons capabilities.

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

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

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.

The crew of Nathan James begin preparations for what may be their most ambitious mission to date.

It is all out war as Chandler must face his fears and confront the greatest threat he has ever encountered.