Guilty as Sin is the eighth episode of the second season of the Netflix exclusive television series Daredevil, and the twenty-first episode overall.
As the firm's trial spins out of control, a figure from Murdock's past returns to deliver shocking revelations about the future of Hell's Kitchen.
At the giant hole they found at Midland Circle, Daredevil tells Elektra that the flashlight he dropped into the hole just hit. They are attacked by Hand ninjas, whom Murdock cannot detect because they are masking their heartbeats. Natchios reminds him that they are using swords, which he can detect.
The two fight the Hand, and Natchios is badly injured. Stick arrives and helps them dispatch the remaining Hand ninjas. They escape in a car driven by Quinn, pursued by the Hand. Murdock is frantic because he can sense Natchios is dying. Stick informs his driver to take them to Murdock's apartment.
At Murdock's apartment, Stick gives Murdock a series of instructions to find the required items to treat Natchios. Murdock does what he is asked, and prays for Natchios's recovery as Stick treats her. Soon, Murdock is able to hear Natchios's heartbeat stabilizing and realizes that she will recover.
As Natchios recovers, Stick casually comments to Murdock that he's known her to recover from worse, which shocks Murdock, who didn't know they knew each other. He angrily asks Stick to explain himself.
Meanwhile, at the courthouse, Karen Page is upset that Murdock has not shown up for court, but Foggy Nelson admits he told Murdock to stay home. Nelson calls Colonel Ray Schoonover to the stand, who describes how Frank Castle saved his entire team, including himself, while at war. He calls Castle a hero, much to the ire of District Attorney Samantha Reyes and Blake Tower.
At Murdock's apartment, Murdock demands answers from Stick. Stick explains that an ancient evil organization called the Hand is in New York City. Their only enemy is the Chaste, an organization to which Stick and Natchios both belong. Murdock scoffs at this, calling it a fairy tale, but Stick assures him that it is true, and that the Hand will bring death and destruction to New York City.
At the courthouse, Nelson calls Dr. Andrew Lee to the stand. Dr. Lee testifies that Castle is in a constant state of "fight or flight" because of his brain injury. He further tells the court that because of the bullet wound to his head, he relives his family's death over and over.
At this point, a young man rises from the gallery and loudly declares that Castle killed his father. Judge Cynthia Batzer orders for Brian to be removed from the courtroom and instructs the jury to disregard the outburst. However, Page and Nelson know that damage has been done to their case. Nelson thinks that Murdock should call Castle to stand to mitigate the damage. Page reluctantly agrees to ask Castle to do this, and to find Murdock and ask him as well.
At Murdock's apartment, he speaks to Natchios as she is recovering. She corroborates everything Stick has told him. She also admits that, against Sticks's orders, she fell in love with Murdock years ago. He admits that when he thought she would die, he felt hollow. He asks her to leave Stick and fight the Hand at his side instead.
Murdock realizes that someone has arrived at his apartment, and Stick slides open the door, announcing that someone is there to see him. Page arrives, and is stunned to see a woman in Murdock's bed. Murdock asks her to go someplace with him so they can talk, but she recoils from him, telling him that his friend could use his help on the Castle case before leaving.
The next day, Murdock arrived at the courtroom to call Castle to the stand. Page barely speaks to him, and Nelson, still angry at his friend's lies, reminds him that he is the only one to hear Castle's story, and asks him to get Castle to recount it again.
As the bailiff brings Castle to the stand, Murdock, with his enhanced hearing, hears a guard whisper to Castle to think about what he wants. Murdock questions Castle, but he is unresponsive. Murdock asks the judge for permission to treat Castle as a hostile witness.
Murdock then makes an impassioned plea to the court, telling them that New York City needs men and woman who will take the law into their own hands, calling them heroes. The gallery applauds him, and he continues, saying that Castle took it too far by killing people, but that he deserves help, not punishment.
Castle asks the judge for permission to speak. He then announces that he would commit the murders over again if given the chance. He becomes more angry, loudly declaring that he is the Punisher and doesn't need anyone's help.
Outside the courtroom, Page, Nelson and Murdock grapple with the fact that they just lost the case. Murdock tells them that he thinks someone got to Castle, but neither of them want to hear it. Both storm away, Nelson saying that he was glad they lost the case, and Page telling him that she's through with him.
At Murdock's apartment, Natchios tells Stick that she wants to leave him to be with Murdock. Stick soberly reminds her that Murdock doesn't know what she is, but she throws him out, declaring that Murdock thinks she can change, and she believes him.
When Murdock returns, he notices Stick's absence, but is happy that Natchios has decided to fight the Hand alongside him. She notices that he has lost the case, and perhaps more, but he simply replies that he didn't lose her.
Murdock asks her to get some rest, and is attacked by a Hand ninja, and is hit by a poisoned arrow. After a fight, he subdues his opponent, and realizes that it's a young man. Natchios emerges from his bedroom with a knife and slits the young man's throat, to Murdock's dismay. Covered in blood, she asks Murdock if he still wants her. Murdock succumbs to the poison, and Natchios sets about saving him.
At Ryker's Island, Castle is processed and a guard brings him to the prison exercise yard, where Wilson Fisk is lifting weights. Fisk tells him that he sees he got his message.