The episode begins with a homeless guy finding a dead body. Next, the team arrives at the scene. Castle and Kate discuss about Alexis’ boyfriend. Lanie tells them that the victim’s body was burnt beyond recognition; but the bone structure proves that it is a young woman. There is a bullet hole at the back of her head and every one of her teeth was knocked out her mouth. But the dental implants could help them identify the victim. The victim is Melanie Rogers and she is an engineer from NJ. Esposito tells them that she made a dozen calls to a number and Kate wants a warrant issued on that number. He also tells them that Melanie made a call to her half sister, Julie at 4 and then her phone went blank.
They bring in Julie who tells them that she and Melanie found each other when their father fell sick. They met for dinner two days ago and she did mention that she is meeting a friend later that evening. They then ask her what she told her when she called her at 4. Julie says that she did not speak to her as she was in a meeting. Melanie had left a message saying that she is in trouble and that if anyone asks her anything, she should tell them XT3. Kate and the team listen to the message and figure out that Melanie was walking though a parking garage and there is a click at the end of the message; it is the sound of a lighter. Ryan tells Kate that the Washington number Melanie called several times, is a burner phone. But then there is a cab driver who remembers dropping her off to the Standish Hotel.
Castle and Kate go to the hotel and learn that the friend from Washington is no one other than Senator Bracken! Later, they confirm that the number belonged to Bracken. Kate thinks that Melanie could have stumbled upon something that got her killed. Kate decides to use this opportunity to bring down Bracken. But Castle warns her that Bracken is known to eliminate all those who came in his way; including her mother and her. So, Ryan and Esposito go to meet Bracken. He feels that he has seen Esposito somewhere. They ask him about Melanie and his relationship with her. He says that she worked for him as an unpaid consultant. They tell him about the Standish hotel. Bracken remembers that Esposito works with Kate.
He lawyers up. Esposito tells Kate that Bracken has a strong alibi; he was at some conference. Kate tells Ryan and Esposito that they ran acheck on the background noises from the voice message; looks like Melanie called from a parking garage next to a construction site. Ryan confirms that Bracken was at a conference at the Widmark Hotel and Melanie was with him. There is a construction site five blocks away; and right next to it is a parking garage. They go to the garage and see a car with XT3 on the plate. They check the trunk and find a blue print of the hotel along with a sniper rifle in a duffle bag. They are shocked when they realize that Bracken was the killer’s main target! Ryan arrives with the information that the security at Widmark stopped a guy from entering the conference as he did not have proper credentials and he was carrying a grey duffle bag.
Kate wants a sketch made. Bracken arrives at the precinct and tells Gates that he is going to attend the upcoming conference as his speech would put him on a national stand and no way is he going to hide because of some whacko who wants to kill him. Later, Kate talks to Bracken in private and it seems that they are going to be stuck with each other during this investigation. The irony of the situation is that she is now protecting the man who killed her mother and also tried to kill her! Gates arrives for updates for the Mayor and Ryan tells her that the serial number from the rifle led to bogus names and addresses. Esposito tells her that the serial from the suspects baseball cap could give them a lead; but that company has around 200 outlets. Gates tells him to start with NJ first.
Castle and Kate are going through the threatening mails sent to Bracken. Kate asks a tired Castle to take a break and he leaves. She then finds a mail whose handwriting matches with the one found on the note from the duffle bag. She obviously does not tell this to anyone. she meets Dr. Carter Burke and tells him about the note. She thinks this is her big break. The next day Kate arrives at work and Castle notices that something is not right with her. She then takes a minute and comes back saying that she has got something to say. But before that Esposito tells her that they have got a lead which suggests that the suspect could also be a mechanic. Ryan and Esposito go to the place where the suspect was hired as a mechanic.
They find out that his name is McManus and they get the address from the employment form. Robert McManus is a schizophrenic and looks like he has been living off the grid. Gates arrives declaring that Robert has been identified by a clerk to be staying at an address for a month. The team barges into the place but finds it empty. Kate goes to talk to the manager and finds Robert walking out of the elevator. But she lets him escape! Kate then tells Castle about the letter she found where McManus threatened Bracken. He accused Bracken for having his son killed who was working as an intern for Bracken’s election campaigns. She saw the pain in his eyes and did let Robert escape.
Gates arrives and tells them that the team found traces of bomb building material in the room; so either the bomb is with Robert or already at the destination waiting to go off!! Kate is upset that she did not perform her duty well. But just then Ryan and Esposito arrive with Robert. They found him hiding on the roof of one of the buildings. But he hasn’t spoken a word since the arrest. Kate goes in to talk to him as she can connect with his pain. But Robert thinks that she is trying to confuse him and does not say anything. Kate loses her cool. Gates interrupts the interrogation and tells Kate that the Feds found the bomb. It was tied to a vest and put in a locker. Bracken sees through things and knows that Kate deliberately let Robert escape. Case closed; at least looks like it.
But Kate is somehow not convinced. The bomb looks too well made and she thinks that a guy like Robert cannot do this; he can barely button his shirt. She feels that Robert is being set up. Also, there was no lighter found on him like they heard on the voice message. Robert doesn’t smoke. So, the C4 on the vest was the bomb they were made to find; but actually there could be another bomb planted for the keynote speech. Kate decides to stop the determined Bracken. The bomb squad sweeps the hotel but finds nothing. Bracken is pissed at her. He walks away. Kate is confused. Just then she hears the sound of the lighter. It is Bracken’s driver. She realizes the bomb is in the limo. She saves Bracken just in time. The driver is arrested. Castle talks to Bracken who thinks that someone must have paid Bracken a great deal of money to do the job.
Castle notes that Bracken is not too shocked with the whole thing. Kate tells them that there was a pair of gloves found in the driver’s apartment with Melanie’s blood on it. Also, there was a fake beard and a baseball cap like Robert’s. Maybe Melanie recognized him and that is why he killed her. Ryan tells the Senator that he is the driver’s only employer. Kate feels that Bracken knows who is behind this but he isn’t telling them about it. Bracken thanks Kate for saving his life. He says that he is in her debt now! She asks him about Robert’s son; but he knows that if he said a no, she wouldn’t believe him.
Bracken then makes a statement to the press, commending the brave men and women of the NYPD. Kate and Castle watch on TV about Ben Moss’ arrest who was paying the driver to kill Bracken. Castle is surprised that Moss is simply arrested and there was no mysterious death!! Kate tells him that this act makes Bracken look like a hero. A story enough to make him President!! The episode ends.