FBI veteran Charles Barker and his new partner go undercover to break up a weapons smuggling ring.
A man behind bars is running a drug trafficking ring in which Barker and Ellis have targeted. Their plan is to set him free so he will lead them to his gang of criminals. The scheme becomes riskier when a they find out an ex-cop is out to settle a score with the ring leader.
Barker tries to stop a Romanian human trafficking ring by going undercover. Meanwhile, Ellis befriends a hooker who's son has been sold by this group.
A jewelry store executive is forced to steal jewels for extortionists who allegedly injected her son with a virus, as Barker and Ellis search for the blackmailers.
The safety of a Chinese nuclear physicist scheduled to testify in the U.S. is compromised and Barker and Ellis must assume protection duties.
There's nothing more dangerous than an FBI agent who's gone rogue, and Frank Oland may be one of them. Barker, who trained with Oland at Quantico, sends Ellis undercover at the security company where Oland works to keep an eye on him. Ellis poses as an unpredictable and sometimes violent U.S. Marine to get close to Oland. The case gets even more complex when Barker searches for Oland's former girlfriend--who just happens to be one of Barker's former girlfriends, too.
Barker and Ellis swing into action when a police officer disappears and is feared murdered. Barker goes undercover with a group of Latino drug dealers suspected in the officer's disappearance, and Ellis goes to work with the missing officer's partner.
Barker goes undercover as a homeless man to solve a series of murders of homeless veterans. The case hits Ellis particularly hard because he's a veteran himself. When Rose finds out that Ellis was in the military, she tries to get him to open up to her about his experiences, but the troubled Ellis turns her down.
Barker and Ellis investigate at a university where a professor may be a Chinese spy. But capturing a spy may not be their only task, when an FBI agent who doubts Ellis' ability, sets him up to fail.
To find an assassin who is searching for an informant who is about to become part of the witness protection program, Barker and Ellis need to infiltrate a high-stakes poker game. This gives Barker and Ellis three jobs, protecting the informant, figure out who is the assassin, and to not lose their $3 million buy-ins.
Barker wants to get rid of an Irish crime family who have their grips on a section of Chicago and is now reaching for Wall Street to expand their business.
Having been set up as a murderer, barker finds himself on the lam, and the Bureau has a relentless agent hunting him down.
Season finale finds Barker discovering a break in a case he's been working on his whole career, but has never been able to solve. With a list of six people involved in the crime in his hand, he hopes to find them before they find him.