A territorial battle is looming in the upcoming episode of TNT's post-apocalyptic drama series "The Last Ship," Cartermatt reports.

In "Long Day's Journey," Captain Chandler (Eric Dane) and his team will track down the Immunes to Northern Florida, where they will discover a compound under the control of Sean (Brian O'Byrne) and Ned (Nick Court). The commanding officer will then realize that the Ramseys are not just leading the sub, but are actually controlling Immune populations on land. 

Meanwhile, Dr. Scott (Rhona Mitra) will discover a secret formula that her mentor, Dr. Hunter (Timothy Landfield), had been perfecting before he was murdered by the Immunes. Although it holds the promise of mass-producing the cure, the formula is incomplete. The paleomicrobiologist then needs her A-game to make it work so they can start saving lives the soonest way possible.

Last episode, Chandler and his squad spotted a British submarine and tried to find out everything they could about it. What they did not realize was that they were being set up for the slaughter. When they found out that the sub was nearly indestructible, they decided to hide USS Nathan James on open waters by enacting a silencing measure.

For a while, the plan worked, but they had not counted on Niels a.k.a Patient Zero (Ebon Moss-Bachrach). He informed the sub's commander about who Chandler was and what his ship was actually capable of. The British were also on a secret mission – they were seeking someone in the navy vessel.

A hostage whom Chandler had taken after the last battle swallowed a flash drive that contained pertinent information. The original plan was that the mole would navigate his way on the ship's deck and dive off when his people let loose torpedoes on the USS Nathan James.

However, the hostage had a bad reaction to the USB and he died. No matter, Niels was still there to save the day for the British. He helped the sub figure out where the labs carrying the cure were located. It turned out that onboard the sub was a group of Immunes who wanted to destroy the cure so they could take control of the States, just like they did to Europe. Although Chandler set off counter measures, he was only able to stop two out of 26 missiles. 

As Celebrity Laundry surmises, it appears that the navy vessel will not be heading back to the mainland for a while.

"The Last Ship" airs Sunday at 9 p.m. on TNT.