Rebecca first appeared as a member of an elite team for a mission run by Michael Westen. The job was to bring an ex-spy selling secrets to terrorists in for questioning. Anson wanted Michael to burn the team by making it look like they were stealing from the target.
It was later revealed that Rebecca was working for Anson when at the airport, she placed a bomb on the target's plane, so the team would be burned for murdering him. After they successfully stopped the bombing, she was seen driving Anson away.
After Fiona was sent to jail, another fellow prisoner attacked her. She revealed that someone called a cell phone under her bed and said if she didn't kill Fiona, her sister would die. Ayn later discovered that whoever it was is working with a dirty prison guard.
While holding Sam captive, Rebecca told him the truth about why she was working for Anson: If she didn't, her brother Trent would die. Michael was able to make a deal with her: If they helped her brother, she would help them take down Anson.
Rebecca revealed that her brother Trent, snitched out a gangster named Wes' father, who eventually died of a heart attack in prison. After that, Wes became obsessed with finding Trent to kill him. Trent went on the lam, and no one has been able to find him. Eventually Anson found out where he was and threatened to tell Wes where if Rebecca didn't do what he wanted.
Michael convinced Wes that it wasn't Trent who ratted his father out. Rebecca told them that she was supplying Anson with travel documents and cash every few weeks and was expecting the next drop in a hotel in Atlantic City.
After learning of Anson's whereabouts, Michael went to visit Fiona in prison. She asked him how he knew and he told her, much to her suspicion, that he learned from Rebecca. He said he can't be sure it was just a trap, but it was Fi's only chance. Fi ended the conversation by saying she trusts Michael, but adding that if Anson slips away again, she'll break out of jail just so she can kick his ass.
After the events in Atlantic City, where a mysterious sniper killed both Anson and Michaels brother Nate, Michael, Sam, and the newly released Fiona went to Sam's girlfriend's apartment to see Rebecca, only to discover that she's gone and leading them to think she was the sniper.
Mike and Fi check a print shop and see that she asked for a set of fake IDs. After some convincing, the owner decides to tell her that he finished early and is ready for her.
However, things went sideways when an unexpected visitor shows up and forces Michael to make him leave at gunpoint just as she arrives. In the ensuing chase, Rebecca shot Michael, who was wearing a kevlar vest, in the shoulder. Michael retaliated by shooting Rebecca in the shoulder before she takes off.
After Michael and Fiona got home, they discovered a blood trail on the stairs, only to find Rebecca inside, still bleeding out from the gunshot. Rebecca tells them that she surrenders, but she didn't kill Michael's brother. They stayed skeptical, saying that she would want nothing more than to kill Anson.
Rebecca tried to convince them she didn't kill Nate and told Michael that either they were good or not, "You decide." After thinking about it, Michael let her go. Before she left, however, she expressed sympathy for his loss of Nate and told him that she hopes he finds who did it.