The episode begins with a woman, who is frantically bolting her doors and windows. She calls 911, gives her address, and asks for help. While she is on the call, the clock strikes midnight and the lights go out. She says that something’s coming for her. The phone falls from her hand, and she is heard shrieking. Castle and Kate arrive at the scene. Castle notices the terrified expression on the victim’s face. He also notices books and other stuff in the apartment that indicates Val Butler, the victim, was interested in the occult.
Amanda, Val’s friend, tells them that for the past three days Val was really paranoid. Amanda had asked her the reason, but she didn’t want to talk about it. She says it’s possible that Val’s ex-boyfriend might have killed her. Freddie Baker, the ex-boyfriend, has a police record. Val had even gotten a restraining order against him. Kate learns that Baker had met with Val right before her death. Baker admits that he did meet her, but only because she called him to her apartment. He thought she wanted to get back together but, instead, she accused him of sending her some package. He says he didn’t have any idea what package she was talking about. When she found out he didn’t send it, she began freaking out and asked him if he believes in the power of evil. He reiterates that Val was alive when he left her apartment.
Kate is informed that Baker’s alibi checks out, so he is not their guy. Castle again points out that Val was freaked out about something supernatural, but Kate doesn’t give it much credence. Castle and Kate look around Val’s apartment for clues. They discover that she has received a package, which contained a CD or a DVD, so they begin looking for a disk. Castle runs a disk that’s already in the DVD player. It plays a creepy video that is a weird mash-up of various images. At the end of the video, a voice announces that the person who sees it will die in 3 days. Castle yells out to Kate, who is in the other room. He tells her Val saw the video, which is why she died and now he will too. At the station, they discuss the disk. Kate feels the killer sent Val the video to scare her, so all they have to do is find out who sent it to her. Esposito and Ryan pretend they aren’t scared, but make excuses to not watch the video.
Kate volunteers to watch it and, although he is scared, Castle accompanies her. Kate admits the video is creepy, but says that it’s the killer who made it that way. Castle notices symbols of resurrection, in the video, from different cultures. Kate and Castle learn from the M.E. that Val died of heart failure, but what caused it, is as yet unknown. Castle is sure that Val saw something so scary that her heart stopped beating. Esposito and Ryan inquire at the place from which the package was sent. A man, who works there, tells them that the owner of the PO Box from which the package was sent, died 3 months ago. After digging deeper, Esposito learns that the package was sent by a guy named Jason Bennett, who lives in New Jersey.
They arrive at Bennett’s house and find that, two days ago, he died at midnight. He too was sent the package. Kate tells Esposito and Ryan to find out if there was any connection between Bennett and Val, besides the disk. Castle calls Wes Craven, and pretends he is working on a film script. He asks Wes for some advice on how to keep away evil spirits. Wes says it’s always a good idea to find out the source from which the evil spirit originated. The next day, Ryan and Esposito tell Kate that they couldn’t find any connection between Val and Bennett. Castle arrives and tells them that he circulated the images from the video amongst his followers on the internet. One of them recognized the image of an inn and where it’s located. They learn that both Val and Bennett had stayed at that inn on Nov 2008. Kate and Esposito visit the inn.
The manager tells them the rooms that Val and Bennett were staying in were both reserved for people involved in the trails at the courthouse. Kate concludes that the murders are connected to some trial held at the courthouse on Nov 08. The manager says there was only the trial of Nigel Malloy, a serial killer, going on at that time. Kate is informed by Ryan and Castle that all the images in the video are connected to Nigel Malloy and the murders he has committed. She is also told that both Val and Bennett were witnesses. Kate concludes that Nigel is killing all the people who testified against him. Castle tells her that Malloy died in prison 3 years ago. Kate and team learn that Nigel had a brother named Leopold, who was an accomplice in the murders, but plead insanity and was sent to an asylum. They also learn that Val had gone to meet Leopold on the day she died.
Kate and Castle meet Leopold and he says Val had come to meet him to ask if he had sent her any video. He points out that he has been locked up for years, which proves he is innocent. He mistakenly lets it slip during the conversation that he knows about Bennett’s murder, although he was never informed of it. Ryan informs Kate that Nigel’s body has disappeared from the cemetery. Esposito tells Kate that the witnesses are all being killed in the order of their testimony, so the third person on the list might be a guy called Mark Heller. He says Heller received a disk 3 days ago, which means he is due to die tonight. They learn that Heller watched the video, freaked out and went to his cabin in the woods. Kate and Castle head for the cabin.
On the way, Kate gets a call from Ryan, who tells her that none of the other witnesses received a disk. He adds that the first three witnesses had something else in common. Before he can tell her what it is, the call disconnects. Neither Castle nor she can call back because their cell phones don’t have any reception. They arrive at the cabin and meet Heller, who is waiting to die. While they are talking, the lights go out. Kate looks out of the window and sees that someone’s out there. She decides to check and hands Castle a gun on the way out. She sees someone in the bushes outside the house, who makes a run for it on seeing her. She chases after the person, but loses him/her.
Heller confesses to Castle that he too has blood on his hands. Castle asks him what he has done, but Heller says it doesn’t matter because they are anyway going to die. Castle argues that it matters because it could be the key, to them getting out alive. Kate catches the person she was chasing and turns out it’s the nurse from the asylum. She says she loves Leopold and he is the one who send her to protect the witnesses, not kill them. At the cabin, Heller reveals that a person named David Collier was arrested by the police for the murders, before Nigel was caught. Heller along with the other two witnesses had wrongly indentified David as the killer. David couldn’t take the humiliation and electrocuted himself in prison. Heller says David had a daughter named Amanda.
Castle recalls that Val’s roommate’s name is Amanda. Amanda enters a while later. Castle and Heller are both hiding. Castle distracts her, while Heller hits her on the head with a large bottle of holy water Castle brought with him. At the station, Esposito informs Kate and Castle that Amanda used a powerful taser on both Val and Bennett, which caused their hearts to stop. Ryan tells them that Nigel’s body was never buried because it disappeared right after his death, so the cops had buried an empty coffin. At home, Castle waits for it to strike midnight, before he goes to the bedroom with Kate. The episode ends at this point.