When the fourth season opens, it's sixteen months after thwarting the coup in America and the Nathan James must face yet another global disaster. The question remains, where in the world is Tom Chandler?.

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.

The crew searches for one of their own as enemies close in on all sides. Slattery is haunted by visions of the past.

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 unhappy when an old foe resurfaces.

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

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.