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

While XO Slattery struggles to evade a submarine, Chandler and his team infiltrate a compound on land.

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

With Dr. Scott on the verge of a breakthrough, Chandler and his team set out to land in search of much needed supplies and materials for her lab.

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.

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.

Nathan James finds itself trapped between the submarine and civilian blockades.

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.

CNO Tom Chandler is sent to Asia to investigate a possible mutation of the Red Flu. Captain Slattery and his crew deliver cure to Southeast Asia but there may be an unexpected threat in the region.

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

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

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.

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

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