The episode opens with a retrospective of various aspects of the Sarah Holt case and picks up where Chapter 11's flash forward ended - the McDeeres fleeing their home which has been attacked by Kevin Stack's men. Mitch, Abby, Ray and Claire arrive at a hotel where they meet Tammy. Mitch instructs Abby and Claire to go with Louis Coleman, who is on the way. Mitch, Ray and Tammy leave ahead of Louis' arrival.
After the opening credits, the main episode picks up two days before the events in the opening. The four are piecing together the Sarah Holt case and have figured out that Kevin Stack is using people - including Sarah Holt - to kill terminally ill patients ahead of when they would naturally die so as to save Noble Insurance the cost of paying for their benefits. Abby suggests going to the Feds but Mitch points out that it's a circumstantial case and they can't go with a theory. They need hard evidence and while pursuing it, they will live their lives as usual so as to not arouse suspicion.
Stack enters Alex's office. She is upset that Mitch has deciphered Moxon's numbers. Stack calms her and says Mitch won't do anything until he has hard evidence and everything he has is circumstantial. He tells Alex that Mitch is exactly where they want him - working.
Mitch arrives to meet with Gerald Sykes. Gerald was Mitch's first paying client and Mitch wants to help him. He has been arrested for robbery and attempted murder. Despite insisting that he was never there, the prosecution has a witness who identified him as well his DNA on the barrel of the gun used in the shooting. When Mitch tells him that he needs a viable defense, Gerald tells him a story he passes off as the truth.
In court, ADA Gordon Shanley is telling the jury that this is one of those open and shut cases given the body of evidence. Before Mitch gives his opening statement, Gerald reminds him that he is his lawyer and since he can't refute Gerald's story, he has to defend him.
Mitch begins by stipulating that Gerald was there and his DNA is indeed on the gun. He tells the jury that these facts are a result of a very different scenario the prosecution has not considered. In fact, Gerald was the victim. He was robbed by a desperate gunman and in struggling for the weapon, it went off wounding the other man. Gerald, who has a record, foolishly fled the scene. The man had no other way to explain to police how he came to be shot so he blamed it on Gerald. Anna, Gerald's girlfriend, is upset by all this and runs out of the courtroom.
At the office, Dimitry Portnoy - with Tammy watching - is trying to break into Sarah Holt's laptop. He first finds Sarah's travel itinerary, which matches up with the locations of Noble patient deaths on Tammy's list. He finds a second file, which appears to contain pieces of a program that have something to do with a ventilator and Margaret Whitaker, the woman Sarah is accused of murdering, used a ventilator. Tammy updates Mitch on the findings as he hurries off to meet with Gerald.
Ray visits a tattoo artist who works close to an Army base. The man confirms that the tattoo seen on Mitch's pursuer is for the SOA, an elite corps of Army medics who are embedded with special operations units. Ray is warned that these are serious soldiers who should not be crossed.
Mitch, Gerald and Anna are meeting and Gerald tries to explain his made up story to Anna. Gerald begs Anna, who was warned by family and friends not to trust a man like him, to believe in him. She says she does not and leaves the room in tears.
Danielle Moxon is visiting Abby and the two are going over a pile of Martin's documents. Abby finds an unopened letter from the bank which Danielle figures has to do with her mortgage. When Abby opens it, it turns out to be a notice for an overdue safety deposit box fee. Danielle did not even know Martin had a safety deposit box.
In court, ADA Shanley says he cannot call his first witness because the DNA is from a crime lab under quality control investigation and their results are not trustworthy. Mitch is suspicious of the timing of this information and demands a mistrial, which Judge Kerzan denies.
Tammy visits a local medical equipment supplier and has a look at a ventilator identical to Margaret Whitaker's. She has a flash drive which contains the program Dimitry recovered. She inserts the drive and dons an oxygen mask. Nothing happens. Tammy removes her mask and shortly thereafter the machine beeps. They discover that the program ignored Tammy's removal of the mask and continued recording as if Tammy was still breathing. It somehow bypassed the operating system and continued to make everything look normal.
At court, Mitch tells Gerald the bad news - there will not be a mistrial and they cannot introduce a new theory. He tries to encourage the distraught man that they can still win.
Abby and Danielle arrive at the bank to check out Martin's safety deposit box. It is located in the most private area of the bank. They open the box and find keys to three other, larger boxes. Two contain dozens of patient files and the third $500,000 in cash. They leave the money and take the files, which Mitch, Abby and Tammy review that evening. Tammy tells them about the override program and Ray arrives with a military photo of Stack with the two men - named William Herman and Vincent Mercer - who chased Mitch. They are also SOA Army medics. Abby is keen to turn everything over to the Feds, but Mitch tells her that Sarah Holt is still his client and he is obligated to defend her.
Mitch meets with Sarah the next morning; bugged briefcase in tow. At first she denies all knowledge, but when Mitch threatens going to the Feds with everything, she opens up to him admitting that she did kill Margaret Whitaker and the others. She also insists on referring to Stack as 'a great man' and tells Mitch he has no idea of the motivation behind the killings nor of the breadth and depth of the path he is on. She says he wants to speak to the US Attorney as she has information to trade. She says she is not going to prison for life and is ready to talk. While continuing to glorify Stack, she tells Mitch that if Stack knew that they had had this meeting, he would come after both of them. Unbeknownst to them, Stack does know as his man is listening in on the bug in Mitch's briefcase.
After the meeting, Ray calls. He tailed the two men to a Noble satellite office and after they left the car, he placed a tracking device on its underside. As they talk, Mitch is on his way to the US Attorney to convey Sarah's desire for a deal. Diane Ruckeyser has no desire for a deal. She will meet with Sarah and listen to what she has to say. Mitch tries to impress upon Diane the scope of the situation, including that Sarah is a pawn in a greater conspiracy. Diane is happy to conduct her own investigation but Mitch warns her that if the whole thing breaks, how she handles it could make or destroy her career.
At the office, Abby and Tammy review the patient files found in Martin Moxon's safety deposit boxes. The find one for a man named Gabriel Lyons, who was killed on the 8th. Abby thinks that's impossible because it's the day Sarah was arraigned.
Mitch and Diane resume their meeting and Mitch suggests there are at least 12 murders that Sarah committed. During their conversation, Abby calls to tell her husband that there are multiple murderers. Mitch shares this with Diane and forcefully tells her to talk to her bosses and make a deal with Sarah. She asks him for a few hours.
Sarah is led back to a meeting room. The guard tells her that it's her lawyer with some kind of an emergency. Sarah arrives to find Kevin Stack, who questions her loyalty to him and the mission. Sarah unequivocally tells him that she has proven her belief in and loyalty to the mission; she would never turn on Stack. He says that's all he needed to hear.
Mitch and Ray meet at the courthouse to share information. Ray tells his brother that while he's keeping an eye on Stack's men, they in turn are keeping an eye on Mitch. Upset, Mitch tells Ray that Gerald is fighting for his life and deserves better than he can give him. Ray tells him that if he's really convinced that Gerald is innocent, he needs to go into the courtroom and not let the jury write him off.
At the trial, the prosecution is questioning the victim on the stand, who identifies Gerald as the shooter and gives a step by step accounting of how he was robbed and shot. As Mitch begins his cross-examination, Gerald launches in to a series of angry outbursts, which continue despite the judge's orders to keep quiet. Eventually, Gerald runs across the courtroom and, before guards can restrain him, punches Mitch in the face.
Judge Kerzan brings Mitch an ice pack and asks if he would like medical attention. He declines saying that it's mostly a bruised ego. She grants a mistrial saying that Gerald's actions have tainted the jury. Mitch offers to continue as counsel for the retrial which her Honor also declines.
Back at the office, the four discuss the developments of the day. Tammy gets off the phone having spoken to one of Noble's supposedly deceased clients. It turns out that three of the files have dates of death in the future. Right then, the US Attorney's office calls and requests Mitch's immediate presence for a meeting. Ray tells his brother to go out the side door as Stack's men are parked out front.
On the way to the meeting, Mitch's briefcase sets off an alarm at security. In a hurry, Mitch leaves it with the guard. Upstairs, US Attorney Franklin Shore tells Mitch that they don't make half-blind deals with serial killers. They are willing to offer the possibility of parole and concurrent time if the killings cross state lines. Mitch is given one day to convince Sarah to take it.
On his way out of the building, Mitch is detained by the security guard, who tells him that a military grade high-tech listening device was found in his briefcase. While the guard wants to know what he was trying to record, Mitch realizes that the brief was present at his meeting with Sarah, where she said she was ready to talk. He ignores the guard and sprints out of the building.
Mitch rushes to the jailhouse, but arrives too late - Sarah is dead. With no signs of trauma or injuries of any kind, the warden is not open to Mitch's protest that she was murdered. He says there will be a standard investigation and Mitch will be contacted if anything is found.
As he is leaving the jail, Mitch runs into Gerald and Anna. Gerald says his new lawyer got him acquitted and he was just processed and released. He thanks Mitch and tells him that it was a real stand-up thing on his part - to take a beating for a mistrial.
Back home, Ray has searched the home for bugs and provided everyone with new phones. Meanwhile, having gathered the evidence, Mitch will turn it all over to Louis in the morning.
Late at night at Kinross & Clark's offices, Andrew Palmer walks by Alex's office and hears Stack's voice lamenting the loss of a good soldier. When he hears them making plans to go after Mitch next, Andrew rushes to call Mitch and tell him he has 90 seconds to get out of the house. Outside, the SUV with three of Stack's men has just arrived.
The final scene takes place one hour later and is a continuation of the opening sequence. Louis arrives to pick up Abby and Claire and wonders where Mitch is. Meanwhile, Mitch, Tammy and Ray are pulling up in front of a high school gymnasium. It is the place Andrew and Mitch first met.