Semper Fidelis is the seventh episode of the second season of the Netflix exclusive television series Daredevil, and the twentieth episode overall.
Murdock and Foggy take on the DA in the trial of the century, but their client refuses to play along. Murdock struggles to balance his dual identities.
At the courthouse, jury selection for the trial of The People vs. Frank Castle takes a very long time. After interviewing over 400 potential jurors, the defense and the prosecution finally approve a panel.
At the Nelson and Murdock law offices, Karen Page, Foggy Nelson and Matt Murdock talk about how to proceed with Castle's defense. Nelson believes that the best way to proceed is to convince the jury that Castle was suffering from Post Traumatic Stress Disorder when he committed the crimes. Murdock agrees to prepare an opening statement based on PTSD as long as Castle agrees. Page offers to visit Castle to get his permission.
Page visits Castle in prison and explains their idea, but Castle rejects it, saying that he was not suffering from PTSD and to pursue that in court would be an insult to the many veterans who honestly did suffer from it. He asks Page if she found anything else out about his family's murders, and they go through her files together.
Back at the office, Murdock works on his opening statement when he receives a phone call from Elektra Natchios. She tells him that she discovered the identity of the person who encoded the Yakuza ledger that they found at the Roxxon offices. He repeatedly tells her that he's too busy with the Castle case to get involved. Nelson interrupts, asking for Murdock's help looking at the Dogs of Hell witness statements. Murdock tells him that he will as soon as he's done on the phone. He reluctantly agrees to meet Natchios that evening.
Philip Cabroni is at his apartment with two Korean prostitutes. After the two leave, he is startled to find Natchios and Daredevil waiting for him. They threaten him until he agrees to decode the ledger. At first he offers to give them the matrix he used to encode it, but Daredevil orders him to decode it himself. He tells them that the ledger lists shipments coming into the city, and reports the location and time of a shipment that is arriving later that evening. Before they leave, Daredevil warns Cabroni to find better business partners, and Natchios tells him to kill his decorator before knocking him unconscious.
Nelson is working late at the office, looking at photos from the Castle case, when Page arrives and offers him coffee. She tells him that when she and Castle looked at the medical examiner's files on Castle's family's deaths, Castle claimed they were wrong. Page suggests that Dr. Gregory Tepper, the M.E., falsified the autopsy results. Page offers to call Murdock to tell him this, but Nelson says he'll do it instead.
At a railyard, Natchios and Daredevil find the railcar that was mentioned in the Yakuza ledger. When they open it, they are confused to find it full of only dirt. Just then, they are attached by the Yakuza. After a long battle, Natchios is injured but they have managed to incapacitate their enemies.
At Murdock's apartment, he stitches up a wound on the back of Natchios's neck while she jokes that she'll never be able to cut her hair short. She asks him what he tells people, especially women, about his scars. He jokes that the women he brings home are too busy enjoying themselves to ask questions.
They compare scars, he pointing out those given to him by Nobu, whom Natchios knows by reputation to be Nobu Yoshioka. Murdock asks Natchios where she went after the incident at Roscoe Sweeney's mansion. She replied that she went as far away from Murdock as she could because he deserved better. He tells her to get some sleep, and eventually falls asleep himself on a chair in the living room.
In the morning, Murdock is frantic because he overslept and is due at court. Natchios tells him that she will try to find out why the Yakuza had a railcar full of dirt and wishes him a good day at court as he rushes out.
In the courtroom, Nelson is panicking because Murdock is so late, and Page asks him what is going on with Murdock. The judge asks the prosecution to make their opening statement, and District Attorney Samantha Reyes makes a very compelling one.
Murdock still has not arrived, so Nelson is forced to give the opening statement. Although he falters at first, eventually he finds him rhythm and is able to describe Frank Castle as a man who was a military hero who returned from war to see his family brutally murdered, murders that the D.A.'s office tried to cover up. Midway through this statement, Murdock arrives, clearly out of breath.
In the hallway, Murdock apologizes to Nelson and Page, who are both frustrated that he was so late, but he tells Nelson that his opening statement was great. He offers to make it up to them by being the one to question Dr. Tepper the next day. He asks Page to meet him that evening to catch him up on everything he's missed. Nelson agrees, but is still clearly upset.
That evening, at Murdock's apartment, Page and Murdock go over the files they have on Tepper, and develop a strategy to get Tepper to admit to falsifying the autopsy reports. They reminisce about the night they met, and how Page was saved by the Devil of Hell's Kitchen. This leads them to discuss Daredevil's vigilanteism, and then Castle's. When Page admits that she thinks maybe Castle was right to do what he did, there is awkward silence before Murdock suggests that they are both exhausted and should call it a night. Page leaves after Murdock promises that they'll have a real date the next time.
Murdock, annoyed, speaks to Natchios, who had been eavesdropping from upstairs. He warns her that Page is important to him and so is his job. She then shares with him all the construction projects in Hell's Kitchen that would involve shipping so much dirt. Murdock recognizes one of the sites as one he sensed on a map of the city when he went about Yoshioka. He had assumed that Yoshioka wanted the site for Wilson Fisk, but now he considers that perhaps he wanted it for himself. Murdock reminds Natchios that he has to be at court in the morning, and she leaves.
In the courthouse, the prosecution finishes questioning Dr. Gregory Tepper about the autopsies of Castle's victims. When it is time for cross-examination, Murdock beings to ask Tepper about how many previous autopsies he'd filled out forms for. But then Tepper surprises the court by asking to make a statement about something he had done. Concerned, Judge Cynthia Batzer orders the court cleared of the jury and the gallery.
Once the only the judge, the prosecution, the defense, and Tepper are in the courtroom, Tepper admits to falsifying the autopsy results of the Castle family, along with a John Doe who was killed the same day. He claims that he did it because people threatened to kill his family if he didn't. Clearly frightened, he said that the previous night, a woman came to him, one with a foreign accent who wore a mask. She threatened to kill him if he didn't confess to his wrongdoings in court. The prosecution and the defense angrily accuses the other of threatening the witness. The judge orders all of Tepper's testimony stricken from the record. Nelson asks for a mistrial, but the judge refuses.
Murdock follows Nelson into the men's room, locking the door behind them. Nelson is furious that Reyes sent someone to threaten Tepper the previous night. Murdock tells him that it wasn't Reyes, but Natchios. Nelson is confused, remembering Natchios from college as a diplomat's daughter and a debutante. Murdock explains that she is back in New York City and is dangerous.
Murdock stammers out that the Yakuza were still in New York, and that he has been working with Natchios to find out what they're up to. He admits that Natchios was the wealthy potential client who had deposited a large sum of money in their account. He tries to tell Nelson more, that the Yakuza are funneling money into something dark that must be stopped, but all Nelson can hear is that Murdock has lied to him again. He yells that he will no longer count on Murdock for anything, and tells him that he'll let Murdock tell Page about Natchios, before storming out, Murdock following.
Page has heard the yelling and asks first Nelson and then Murdock to tell her what's going on, but they both refuse. Murdock tells her that he has to go but he'll talk to her the following day, and she mutters that maybe he won't before leaving.
Daredevil find Natchios outside of the Midland Circle construction site, and furiously tells her that she ruined his case by threatening a witness. He warns her to stay out of his life as Matt Murdock, and she agrees, claiming that part of his life was boring, anyway. Still angry, Daredevil fights the men guarding the site, with Natchios arriving afterwards, sarcastically reminding him that he didn't want her help.
Inside the building site, he informs her that they are alone, but he is shocked to sense a large hole. He takes a flashlight from her and drops it. After a few seconds, she asks if it has hit bottom, and stunned, he says it hasn't. She sighs and asks him to tell her when it does.