A Russian scientist and an Britsh MI5 agent are suspected of collusion. Jonas is sent to London to team up with the agent. However, things get complicated as Jonas had been engaged to the agent's wife earlier.
In Montenegro, Bob has a moral dilemma when he disagrees with the team's mission. Tiffy discovers some information about Molly's past and decides to look into it further.
Charles goes undercover among gang members from his old neighborhood when it's discovered that they've been stealing explosives and weapons. Meanwhile, Tiffy gets hurt at work and Mack goes after her attackers.
Jonas goes on a solo mission, enlisting the help of some local militants to hunt down a terrorist known as "The Butcher". Charles is still recovering in the hospital, Mack takes on the task of arranging Hector's final funeral preparations, with the help of the other wives and Bob has been ordered to deal with the rescued journalist. Ryan must deal with the man sent by Washington to oversee the cover story.
The Unit is in Lebanon when Charles is seriously wounded. They must think and act quickly to save his life. On the Home Front, Tiffy's problems continue to build when a man attempts to tow her car. The women stand up and fight to protect her.
Mack, Charles and Jonas are assigned to protect an American musician while she tours the army camps in Iraq, while Bob is assigned to transfer a prisoner from a high-security prison.
Jonas must recover a chip containing information that could prevent a possible terrorist attack.
The team travels to Abidjan, Ivory Coast to aid personnel from the American Embassy. They must get the Americans and their families out of the area. On the home front, Jonas’s daughter has enlisted in the Army and he wants to train her as well as to test her resolve.
The Unit is back together and ready to take on their next assignment when a bomb filled with a nerve agent stolen from a nearby base is discovered to be on its way to their home. On the home front, Jonas and Molly make plans to spend time together, Mack is ordered to move out of his home, and Kim proposes a new show for the station but ends up handling a crisis.
Jonas works out a plan and the team reunites to clear their reputation. Kim is working behind the scenes to keep the CIA away from the other wives.
Jonas is still in hiding, Mack and Hector are still imprisoned, Charles is on the run, Bob is in Mexico, working for the CIA and Colonel Ryan is again called to answer question before a Congressional hearing.
