The Unit is a covert team of U.S. Special Forces operatives who must undertake missions around the world. The latest newcomer is Bob Brown who joins Jonas' team and they set out to rescue an airliner filled with European businessmen who have been hijacked by terrorists. Meanwhile, Bob's wife Kim is struggling with how much control the Unit has on her own personal life.
The team, minus Bob, are in search of a fallen Chinese satellite. This quickly turns into an opportunity to capture one of the world's most wanted terrorists. Meanwhile, Bob is questioned about the Unit's role in the rescue of the hijacked plane. Molly decides to visit the Unit's psychiatrist about the shooting at her home. Kim is frustrating about moving and then comforts a woman who has just learned her husband has died in combat.
The Unit is sent to Los Angeles to protect Mexico's drug minister who has been threatened with assassination and soon his wife and sons are kidnapped. At the base, a former Unit wife makes a return appearance in the hopes of luring the Unit members away. Tiffy is upset when Ryan orders Mack to take time off.
Jonas and the team carry out an assasination of a terrorist in Spain. However, they soon find out that the government called off the mission and will now not protect them in the country which means there only hope is to escape. Back at the base, Molly learns that her daughter Betsy wants to drop out of college and Kim thinks about taking a college course herself.
The Unit must try to get a listening device to an agent inside the Iranian embassy where U.S., Iranian, and Russian diplomats are meeting. Many are speculating that the Russians are attempting to sell the Iranians material to make a nuclear weapon. Meanwhile at the base, Tom tries to end his affair with Tiffy but she won't listen to him and Kim notices Tiffy at a motel room and does not know what she should do.
The crew must fly to Afghanistan to assassinate a high ranking member of the Taliban. However, one of their team helicopters ends up going down in enemy territory, placing the entire crew in jeopardy. Back at the base, Molly confronts a friend and retired Unit veteran about his addiction to painkillers and Kim ends up getting a job at the local radio station.
Jonas and his team must track down surface-to-air missles before they are smuggled out of Brazil after a deal with a drug lord falls through. Jonas gets help from a local boy who informs the team where the SAMs have been taken to be shipped. Meanwhile back on the base, Kim ends up causing even more trouble when she insists that the “Family Readiness Group” deals with what she deems more serious issues. Also, Williams tries to find a way to tell the woman he wants to marry that he is actually a Unit member and not a clerk on the base like she believes.
After Bob gets his cover blown in Africa, he tells Jonas to cancel a visit a dignitary is taking to the area because of the danger. However, the official refuses and something shocking is quickly learned about why he really wants to go there. Meanwhile, Kim has an encounter while at the radio station and Molly gets offered a real estate opportunity.
Keith Soto returns to the base for a reunion and it's quickly discovered by Jonas and Col. Tom Ryan that he is a newspaper reporter who is writing an article that will expose the Unit. Jonas decides there is only one way to get him to not print the story. Meanwhile, with some help from Tiffy and Kim, Molly tracks down the woman who scammed $40,000 of the women's investment fund.
The Unit ends up detaining a former Yugoslav general who was wanted for war crimes and then allows lets the U.N. take credit for their capture. However, the criminal soon escapes U.N. custody and he is now seeking retaliation against Jonas for capturing him. Meanwhile at the base, Tiffy is convinced that Mack has decided to re-up with the Unit and she's thinking of divorcing him, and Kim is the recipient of some disturbing news.
A former member of the Unit is locked up in a Bulgarian prison and Jonas and his team must go to help him escape in order to find one of the world's leading arms dealers. On the home front, the women meet a young man who hopes to be part of the unit someday. However, in order to get extra money to take care of her aging mother, Molly takes a one time recruiting job to hire the man away form the military. Needless to say, members of the Unit family are none to pleased at Molly's new job.
The team is assigned to stop of shipment of smuggled diamonds and Bob is conflicted when he sees one of the men helping themselves to the diamonds. On the home front, Molly and Kim are raising money to help the men and women serving in Iraq. Tiffy debates the war with protesters from a local school.
Jonas and Molly celebrate the overdue presentation of George Blane with the Silver Star for his service in Korea, but are interrupted by the discovery that their nephew is beating his wife. Jonas attempts to remedy his nephew's behavior by sharing memories of his father after he returned from war.Meanwhile, Mack offers help to a jet that needs assistance to land after the pilot dies in mid flight and the jet flies into a restricted area. Piloting the jet is a former Ranger, with an alcohol problem and Mack calls Bob into help him.
Jonas is assigned to protect an US Senator on a humanitarian mission to an Asian country. Although he has been secretly ordered by the President of the United States to meet with the former Prince who is planning a revolution against the current regime. On the home front, Molly, Kim and Tiffy work with Jeremy in planning a surprise for Crystal.
The mission is to take control of a South Korean submarine to assist in the defection of a North Korean Scientist. The team find themselves confronted by several roadblocks. On the submarine, the South Korean Captain does not want to take orders from Jonas. On the home front, Kim has a dream that shares many similarities to the current mission. Ryan thinks that Bob told Kim about the mission and threatens to scrap the mission and wants to fire Bob.
The team is sent into Iran to set up a system that can detect Weapons of Mass Destruction. The mission goes off kilter when civilians become involved.On the home front, Tiffy runs into a dilemma while doing her community service. Molly and Kim are helping Jeremy and are confused by Crystal's behaviors. Mack finds himself in trouble.
The team goes to New York to protect a foreign dignitary at the United Nations building. A bomb is discovered and they must diffuse it. Molly and Tiffy travel to Vietnam to attend a War Memorial Service. A mother of a POW asks them to look for her missing son.On the home front, Mack rejects Crystal's advances and she threatens to tell Tiffy.
The team participates in a unique competition known as the CT Games that puts them up against other Special Forces units from around the world. Things take a bad turn when one of the teams appears to be taking things too far to win. Kim must travel to Utah to save her job and finds herself meeting an ex-lover. She spends some time getting reacquainted with him.
The Unit is sent to Pakistan to retrieve three suspected terrorists when they run into trouble with the local forces. They find a U.S. base with a small force of troops that do not respect their commanding officer. Jonas takes control of the combined group and prepares them for the impending attacks.
The Unit travels to Israel to learn some new techniques in terrorist tactics and how to defend against these tactics. Charles becomes interested in a Sergeant in the Israeli Army, yet things turn very dangerous when they go off alone together. On the home front, Tiffy finds some WWII memorabilia and begins soul searching on what she should do with it.
Bob and Hector head to New Guinea to retrieve a black box from an Army aircraft that was shot down. The wreckage is located on sacred grounds and they need permission of the local tribes to retrieve the item. They both must face their own battles to gain the acceptance of the tribe in order to succeed with the mission. On the home front, Crystal tells a reporter about Mack to get even with him for rejecting her. This action endangers the entire team as well as the National Security of the country. Mack must enlist the aid of the other Unit members to neutralize this threat.
The Unit is called in to help out the local SWAT team when a prominent school in Virginia is taken over by shooters. They must determine how to free the hostages without the students getting injured. On the homefront, Lissy has a young man interested in her, which turns into a delicate situation as he is the son of an Officer. Kim further complicates this matter, when she defies Tiffy’s orders and Lissy pays the price.
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 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.