Seven years ago, Christopher infiltrates the home of Daniel Brooks posing as a repairman. However, he makes a call to confirm that Brooks is the intended target, and Christopher's contact, Donnelly, says that Brooks got himself into a mess. Christopher takes out a gun, goes back inside, and shoots Brooks dead.
Now, Christopher is practicing tai chi at his studio when Winston informs him he has a call from an old friend, Donnelly. They agree to meet Donnelly at a bar that Christopher frequented seven years ago. As they arrive, Christopher explains that he used to hang out there with Donnelly. Winston refuses to go with his friend, who enters his bar and meets with Donnelly. Donnelly informs Christopher that someone has hired an assassin, as good as Christopher seven years ago, to kill a woman. When Christopher asks for more info, Donnelly says that he can't risk giving any more info, and he contacted Christopher as a favor.
Outside, Christopher gets in the car and tells Winston that they're taking the case. He admits he doesn't know anything about who wants the woman dead or why, but she's the wife of the man he killed seven years ago.
Back at the warehouse, Winston finally figures out how to scan the photo using the new equipment that Ilsa has bought them. Christopher admits that he has no idea who hired him, and either the Old Man or Donnelly gave him his orders. The target is Rebecca Brooks, age 35, an economics professor at Northern Cal University. Her dead husband was also an economics professor at the university. Winston confirms that Rebecca is a member of several social-networking services. As they talk, Guerrero comes in and they realize that he's broken his glasses. He explains that his pair fell into a meat grinder and the new ones won't be ready for a day. Christopher explains that Donnelly brought them the case, and he wants Guerrero to lean on him for more information. They track down where she's meeting her next date, and figure the assassin will locate her as well. Christopher heads out, planning to pretend to be her date and get her out of the restaurant. As he leaves, Winston warns Christopher that Donnelly can't be trusted. Since Guerrero can't drive, he needs Winston to take him where he needs to go.
Ames drives Guerrero, who tells her that he's going to a bar to see an assassination broker, and she's to stay in the car because she's not ready.
As Winston goes, Ilsa arrives early from Hong Kong and wants to discuss the accounting with him. When she learns he's heading out on a job, Ilsa wants to go with him. Winston tries to deter her, noting that she's been a lot. Ilsa reminds him that he's now her employer, and insists that she can handle it.
Christopher arrives at the restaurant while Winston and Ilsa watch from the surveillance van. He's surprised to learn that Ilsa is there, and Winston doesn't tell her that Christopher killed Rebecca's husband. Christopher approaches Rebecca and says he's her date, a doctor, and explains that the photo he put up on the dating service is when he dyed his hair. He tries to get her away, but the real date shows up. As they talk, Christopher realizes that the newcomer is the assassin. The assassin hastily leaves, but Rebecca warns Christopher to stay away from her. She goes to the parking lot and Christopher pulls up to her in his car, and tells her they have to go. The assassin manages to get ahead of them, but Christopher shoots the controls on a gate, separating them so they can get away.
Back at the office, Winston tries to identify the assassin, while Ilsa tries to reassure Rebecca. When Rebecca insists that Ilsa has no idea what she's going through, Ilsa describes how Christopher recently saved her life. Once she calms down, Rebecca thanks them and they explain that they believe that the persons ultimately responsible for her husband's death are coming after her. She explains that she and Daniel worked in the field of predictive economics, and her husband was working on a paper predicting baseball park tickets when he died. Rebecca admits that she just applied for a grant to complete his work, and it's stored at the university archives.
Guerrero goes to the bar to talk to Donnelly and asks if he's forgotten anything. When Donnelly says he hasn't, Guerrero thanks him and then loudly announces that Donnelly is now working for Christopher. He also tells Donnelly that he'll visit his daughter next. Before Donnelly can say anything, Ames sits herself down next to Donnelly and claims she's Guerrero's girlfriend. He tells her to leave and she stalks off. Guerrero meets her outside, and she gives him Donnelly's cell phone, which she pickpocketed. He points out he would have already had the contact's name by now, and tells her to drive.
Christopher and Rebecca go to the university while Winston ties into the university's security cameras, shocking Ilsa. Rebecca warns that the clerk, Harrison, has a thing for her. He informs them that Daniel's papers were shipped out right before her husband died, but refuses to give them the address. Christopher claims to be an insurance adjustor and convinces Harrison to give them the address by noting that Rebecca said they were close. When they have the address, Rebecca says it's the family home where Daniel was killed.
Guerrero has the name of Donnelly's contact a lawyer who works for a small investment bank. As he talks to Winston on the phone, he mentions that Christopher killed Daniel, and Ilsa realizes what's going on. When she worries if Rebecca can trust Christopher, Winston assures her that Christopher will protect her.
The assassin arrives at the archives and opens fire on Christopher and Rebecca. They flee into the university and Winston directs them to a chem lab. Christopher gets the class out and then makes a crude flamethrower out of a fire extinguisher. He stuns the assassin long enough for them to escape, and the assassin escapes before the police can arrive.
Christopher and Rebecca get to an outside door, but the police are guarding it. As Christopher prepares to sneak Rebecca out, she worries that the assassin could have been the man who killed her husband. As Ilsa watches on the camera, she admits that Winston may be right and she can't handle it, and leaves.
Guerrero tracks down the lawyer and prepares to torture him for information. The lawyer finally breaks and says that Daniel was blackmailing his firm. He doesn't know about Rebecca, and Ames leaps in. Guerrero calls her off and tries to go back to work, but they both notice broken glass from the skylight. Ames leaps on Guerrero to get him out of the way, but the assassin above finishes off the lawyer and leaves. Guerrero calls Winston, and they both figure that someone has inside information to kill the lawyer at just the right moment.
As Winston goes to help Christopher, Ilsa insists that the whole thing came about because Christopher killed Daniel. Winston reminds her that he said things could get messy, and they all have histories. When Ilsa insists on telling Rebecca the truth about Daniel's death, Winston informs her that Christopher will tell Rebecca himself when the case is over.
Christopher and Rebecca drive to the Brooks home. Rebecca hesitates to go inside, but Christopher tells her that the sooner they go inside and resolve the case, the sooner she can put Daniel's death behind her. Inside, Christopher doesn't find anything and suggests they go to the attic. He finds a hidden safe with a gun and a file.
As Winston get in the car to find Christopher, Ilsa gets in with him and insists on going.
Rebecca reads Daniel's files and realizes that his theory could be used to predict stock activity and manipulate the system. The assassin arrives and cuts the lights, and Christopher says they need to get out through the storm door. Realizing that Christopher knows too much about the house, Rebecca uses her husband's gun and demands an explanation. She notes that the police said that her husband's killer came in through the storm door, and asks if he knows who killed her husband. Christopher finally admits that he killed Daniel. As he tries to tell her he's the only person who can protect her, Rebecca shoots him the shoulder. Christopher tries to get her on his side, but she runs out.
As he drives, Winston tries to reach Christopher on his phone.
Christopher uses a napkin to bind his wound and then goes after Rebecca. She's hidden in the greenhouse, and the assassin starts to come in.
Winston complains that Christopher didn't listen to him, just like Ilsa, and she realizes that he's concerned about his friend. He insists that Christopher isn't thinking straight, and he's trying to make up for the horrible things he's done in the past, and the bad guys know that.
Rebecca crosses the back yard to the pool, and the assassin grabs her. Christopher arrives and the two men fight. The younger assassin initially gets the upper hand, but Christopher stabs him in the foot and knocks him out with a brick. Rebecca prepares to shoot Christopher again, and says that he deserves to die. Christopher admits that she's right, and invites her to kill him. Donnelly arrives and disarms Rebecca, and then explains that he hired Christopher to kill Daniel so he could get the theory. Christopher apologizes to Rebecca, and Donnelly prepares to kill them. However, Winston arrives just in time to kill Donnelly.
Later, Guerrero and Ames return to the warehouse and tell Christopher that they pulled the files from the lawyer's computer. Ames can't resist jumping in and explaining that Daniel was blackmailing the investment bank and was planning to flee to the Cayman Islands. When Guerrero tells her to shut up, Ames reminds him that they only found out about the blackmail scheme because of her. She stands up to Guerrero, insisting she wants some respect. Christopher thanks her and Guerrero reluctantly takes her with him. Ilsa notes that Rebecca has no idea what who her husband really was, but Christopher says it doesn't make a difference to her or anyone else.
Ilsa and Winston meet with Rebecca and tell her that since Donnelly killed the lawyer and the assassin was a hired gun, they have no way to connect anyone else at the firm to Daniel's death. Rebecca tells them that she gave the theory to a reporter at a national business journal. She figures Daniel would have been thrilled to have it published. As she goes, Rebecca asks how Ilsa works with Christopher Ilsa says that she sympathizes, and hopes they can both find the strength to move beyond it. Rebecca confronts Christopher and asks if he thinks that saving her makes up for killing him. She tells him that it doesn't, turns, and leaves. Ilsa asks Christopher why he didn’t tell her the truth about Daniel, and he says that what she needed was him to protect her... and that's what he does.
Guerrero takes Ames to a bar and opens up a tab for her.
As Christopher practices tai chi, Ilsa asks Winston how Christopher can be okay with everything. Winston tells her that none of them are, and that's why they try to make up for their pasts. The phone rings and Christopher tells someone to pick it up. It's a man looking for help. Ilsa looks up at Christopher, smiles, and says that they can help.