The fourth season of The Unit started on September 28, 2008 and introduces Bridget Sullivan and Sam McBride, new members to the unit and the team.
The team is thrown straight from a 5-month deployment to topple a Yemeni terrorist, into a plot to topple the U.S. government. As the U.S. leaders are assassinated, the team jumps in to save the the president-elect who has escaped an attempt on his life. While the team is engaged in the field, their wives are being quickly relocated for their own safety from the plotters.
In an effort to identify the terrorists behind the Vice President’s assassination (Episode #401), Jonas, Bob & Grey pose as regular passengers on a foreign commercial flight to follow a nuclear scientist.
On a mission to rendition a Balkan smuggler of nuclear materials, Jonas discovers that the Unit’s local contact and life-line is also a trafficker in sex slaves.
In the hunt to kill a drug lord, Bob, Jonas and Grey pose as chemists with a formula for turning cocaine into paint for smuggling. Meanwhile, Mack penetrates the cartel as a human cockfighter.
As the condition of Dr. Leon Casteel (who is dying of radiation poisoning) worsens, Tom Ryan makes a discovery.
The Unit deceives a terrorist into believing his bomb plot was successful. Jonas and company produce fake evidence of the attack as Bob tries to goad the terrorist into revealing his accomplices before the ruse is exposed and the accomplices flee. The Unit is forced to rely on a risky con to ensnare a powerful enemy.
In the first of our sweeps episodes, we light the fuse on two explosive storylines: the kidnapping of Betsy in Iraq; and the long-awaited brutal consequences Tom Ryan must face for his adultery with Tiffy.
As the team attempts to rescue Betsy, Tom Ryan and the other U.S. soldiers from their Syrian kidnappers, Mack finally has the opportunity to execute the death sentence placed on Tom Ryan’s head. Meanwhile, Molly, sequestered by the military and reeling from Betsy’s capture, is guided by Dr. Eudora Hobbs on a psychic/psychological journey that could possibly save Betsy’s life.
An important truce has been brokered between two warring tribes in Afghanistan that involves a marriage. The Unit is tasked with escorting the bridal party through enemy territory to the groom’s village, via a mountain route passable only on horseback. The Unit and their motley crew encounter multiple challenges en route in this version of a modern-day western.
Department of Defense official -- nicknamed by us “Dr. Death”-- assigns the Unit with an impossible assault on an Uzbeki lab where anthrax is being weaponized and is days from completion. Dr. Death had a spy within the lab who was discovered by the Uzbekis. One attempt by an indigenous Special Ops team already failed to rescue him.
Coming off the failed mission of the previous episode, where Special Ops soldiers were killed and Grey wounded, Donald Metz (the cavalier D.O.D. official responsible for the failed mission) is forced to join the team on their next assignment when they are rerouted in the midst of their journey home. They treat him to a front-row seat on a perilous operation, where he comes face to face with the realities of war.
At home and on the mend from his gunshot wound, Grey falls in love with an AeroDyne client who turns out to be one of the richest women alive. But when Grey is caught in a lie protecting his cover, his inability to come clean forfeits an opportunity for true love.
Jonas and the team deploy to a casino in Macau, where their task is to regain the services of a vital CIA asset who’s gone over to the Chinese. But the Unit has a more personal stake in the outcome: if they can complete the mission, then the the charges against Bridget (Episode #408) will be dropped. The sting involves breaking into the casino’s safe deposit vault in order to ruin the mark’s reputation with his Chinese patrons. But the plan goes awry when Bob is kidnapped mid-caper and tortured in a terrifying way that may cause him to give up the mission -- and the team.
Having captured terrorist money launderer Isaac Reed (Episode #410), Tom Ryan finds himself unable to break Reed and get him to admit complicity in the terrorist attacks. Knowing he must soon return Reed to his life or the terrorists for whom Reed works will get suspicious, Tom Ryan calls upon Kim, hoping Reed’s affection for her may get him to open up.
Chilean Andes. Jonas and a wounded Mack take refuge in a monastery, where they are protected by benevolent monks. Afterwards, Jonas is conflicted when given an order to steal the monks’ prized possession, the “Spear of Destiny” (the spear that pierced the side of Christ, and which is believed to hold the power to grant its possessor victory in any battle).
After being jacked up on heroin in Macau (Episode #412), Bob -- at home enduring self-detox-- gets assigned a mission in Kansas City. Kim is determined to stop him from using drugs, and goes on the mission as a “watchdog,” setting up Kim to witness the darkest aspects of Bob’s job.
The President orders The Unit to snatch a Nazi war criminal from hiding and deliver him to The Hague. The Catch: Private bounty hunters have been hired to kill the Nazi. The Unit must capture the Nazi first, or battle the hunters for him.
The Unit's cover story is threatened when Carson (ep 411) comes back to try to buy Aerodyne Alliance.
In Washington, Tom Ryan must face his past demons as he contemplates the new role of general being offered to him.
The Unit initiates new team member Staff Sergeant SAM MCBRIDE through his final training exercise. McBrides’s loyalty to the Unit is tested throughout the episode, culminating in a real mission when the team tracks down the assassin of former Unit brother Hector Williams.
The Army wants to send Betsy on a media tour, and Jonas is assigned to coach her on the kidnapping/rescue cover story. After that, she wants to go back to Iraq. But Molly has major concern when she sees her daughter exhibiting signs of post-traumatic stress disoreder.
The Unit and their families are scattered around their community when chlorine gas leaks into the water system, poisoning everyone who is outside and cutting off communication with the outside world. Tiffy, who is supervising detention at the school, manages to seal off the classroom and protect the students with her. Grey is on the road, but secures a number of other drivers in the back of a closed refrigerator truck. Mack, his kids, Molly, Kim and Bob, make it back to their apartment building where they aid other residents to safety. Mack and Bob find a neighbor's scuba equipment and use it to make it to the Aerodyne offices, where they find Jonas and the new recruit, Sam. Jonas and Sam are the only ones with outside communication -- they've located the where the chlorine gas had to be inserted in the system and make ready to remedy the problem and deal with any potential terrorists (it's unclear whether its a massive accident, or terrorist activity).
The Unit is in South American rescuing a leader expected to lead a coup against the existing fascist governments. The man was trained by Jonas years ago and is badly injured. Unfortunately, their helicopter is damaged and, as Bob tries to repair it, Jonas works on helping his old friend. Time is running out, rebel soldiers are on their way. Jonas job is further complicated by the leader's impetuous son questioning his every decision. The guerillas approach as they're about to take off and the gas tank gets shot open. The leader makes a last stand to allow Jonas and his team to escape with his son, whom he appoints to take over. The son in turn, has grown up and asks Jonas to teach him as he did his father.
Also, Molly goes to a memorial service for the chlorine gas victims and runs in to Susan Gillum, the wife of one of the people the Unit was investigating as a terrorist. Susan reveals her husband disappeared the night before the attack and Molly lets Tom Ryan know. Tom tells Molly to meet with Susan and find out what she knows, but Molly refuses saying the woman is fragile and on the verge of drinking again. Tom says, if Molly doesn't, someone else will and does the job himself.
Jonas and Mack go undercover to lay a trap with Drake in order to get closer to the terrorist plot that killed the Vice President.
After a successful mission in Afghanistan, The Unit winds down in a bar.
Jonas and Bob are in Hong Kong stealing a piece of technology. It's a carefully planned mission, involving months of prep so that when the theft is noticed, the terrorist organization, Falun Gong, will be blamed for it. Things go flawlessly until the random decision of a stranger who decided to commit suicide by jumping in front of a subway car foils their escape. Trapped in a Hong Kong subway, Bob and Jonas must improvise and Bridget works a local press contact to get them a way out.
Bob has developed a Russian contact who tells him that the Russians have sent a group of shooters to take out all the terrorists so their connection to the recent terrorist activity. They follow the shooters who lead them to the first terrorist cell, only to learn the Russians have been taken out, along with several of the terrorists. As they track down the rest of the of the terrorists, Sam uses Molly to contact Jonas in order for the terrorists to eliminate the Unit. Jonas, who has no idea Molly was missing, and the rest of the team, must execute a mission that rescues Molly and flushes out the remaining terrorists. Turns out Sam is in deep cover and assists with Molly's rescue but has to make it seem like he was injured in the process so he can return to the group. When Jonas confronts Tom Ryan about not telling about his wife and Sam being under cover, Tom holds strong, but there's a huge rift between them
Tiffy and Kim complicate Tom Ryan's mission by reporting Molly missing after neither Tom nor Bridget take their concerns seriously.
Sam, working in deep cover with the terrorists, manages to get word to Tom Ryan that three cars, loaded with dirty bombs, are being dispatched to unknown locations. With this limited information, the Unit works to locate and neutralize those cars. When they do, they learn that they're all decoys and Sam is with the actual dirty car bomb in Washington. They desfuse the bomb and bring the terrorists to justice. The episode ends with a special Unit wedding between Grey and his newfound love Joss.