The victim this week is Paul Reeves, who was found in the park and was shot in the head a little over an hour before the police arrived. There are no witnesses and no camera surveillance, and with Reeves’ cash and phone missing, it looks like a mugging gone wrong. But nothing is ever that simple. There are remnants of a silencer at the scene, and no signs of a struggle; Paul Reeves’ death was a deliberate murder.

Castle and Beckett question Reeves’ brother, who says that Paul spent most of his time at the office. He didn’t have any enemies, but he was nervous about a meeting that was scheduled the morning he died.

They visit Reeves’ office and talk to his boss Ms. Jarvis, who was unaware of his morning meeting. Paul was an investigator for the government, meaning he looked into facilities that received government funding to ensure the money was going to proper use. His focus was health care, meaning that if someone using grant money didn’t produce results, he had the power to shut them down. Ms. Jarvis gives the detectives all of Reeves’ active files, but with twenty cases on the go, it won’t be easy to narrow down their suspects.

Wondering who scheduled the meeting, Ryan gets a hold of Reeves’ phone records and a call from a pay phone catches his eye. Using video surveillance and facial recognition software (isn’t technology great?) the team is able to put a face to the caller: Jared Stone. Stone is an Occupy Wall Street hacker, and Castle believes that using his computer skills, Stone uncovered something, tipped of Reeves, and got him killed.

Ryan and Esposito go to track Jared Stone, and on the way they have a little heart to heart about married life and parenting. Espo seems to be ready for a more serious relationship, but Lanie isn’t there yet. The whole conversation is pretty adorable.

But the moment is cut short when they spot Stone walking into a subway station, and Espo jumps out of the car to follow him. He follows Stone into a subway car, and once the train is moving he confronts the suspect. As soon as Stone sees Esposito’s badge, he freaks right out, grabs a nearby traffic cop’s gun, and stops the train. He holds the car at gunpoint and notices the glow of Espo’s cell phone in his pocket. Ryan is still on the other end, and has heard enough to know his partner’s in trouble.

Despite looking panicked, Jared insists he’s in charge of the situation, but is confused as to why no conductor has come to investigate the train being stopped. He feels the side of the train, and senses the movement of people being evacuated. Stone demands to know if Espo had a cop at the other end of his phone, and when Espo confirms, Stone grows even more frazzled and pulls out in his inhaler to calm himself down. Espo tries to talk the man down, explaining that he still has time to walk away from this, but once the Hostage Rescue Team are involved, that chance is gone.

The HRT won’t hesitate to shoot him once they breach the train. Stone explains that the HRT won’t touch him, and he opens his jacket to reveal an explosive vest attached to a dead man’s switch (which is basically a pressure controlled detonator; if the guy holding it gets shot and he releases the pressure on the switch … BOOM).

At the precinct, Captain Gates gets everyone up to date on the situation. She demands that the only way to help Esposito is to find out everything they can on Stone so they can tell HRT what kind of guy they’re dealing with. HRT on the other hand, wants to know what kind of pizza Espo likes. Priorities, am I right? Luckily, the subway Espo is on is part of a video surveillance pilot program, so the cops can see what’s happening in the train, while Stone remains oblivious. Bottom

Stone is looking worse for wear on the train when HRT calls his phone. They want to know two things: 1) What are his demands, and 2) Is anyone hungry? It’s becoming clear that Stone maybe isn’t a terrible guy as he allows the HRT to bring food to the platform, and as far as his demands go, he only has one. He wants Erin Wilson released from prison.

Erin Wilson is another hacker who was incarcerated for hacking into a big bank’s system looking for evidence of them colluding with the government. Stone was believed to be an accomplice to the crime, but not enough evidence was found to press charges. Castle and Beckett begin to speculate that Wilson is behind Stone’s actions, and Ryan brings them further proof. He had gone to Stone’s apartment where he found a paper shredder full of documents. As he put the pieces of paper back together, it became clear that they were full of instructions that Stone has been following verbatim. Someone else had planned this whole thing.

Pizza arrives for the hostages, and as they’re handed out, Esposito’s pineapple, olive and double jalapeno (which is ballsy to eat in a hostage situation as spicy food can do crazy things to one’s stomach) comes with a note inside. HRT is planning to breach the train, and they need his help to secure the dead man’s switch. He informs the traffic cop who’s with him, and they await the flickering light that will act as their signal.

Jared Stone has a great sense of movement, as he feels the HRT guys on the train and quickly calls the negotiator to tell them to back off. He doesn’t understand why they’d even attempt a breach, as they don’t know where he is in the train unless they do. He suddenly realizes that there’s got to be a camera on board, and when he finds it, he shoots it to pieces.

Lanie, who has been at the precinct since news broke that Espo was in trouble, goes over the footage they have of the train when she realizes something. As the hostage situation has been playing out, Stone has been having a hard time breathing and it isn’t just his asthma. He’s been getting sweaty yet shivering; he’s coming down with a bad flu, and it’s only a matter of time before he isn’t thinking clearly anymore. Beckett remembers that one of Paul Reeves’ cases had to do with a missing flu virus. Everything that’s been happening is connected; they just have to figure out how.

Esposito has had the same realization as Lanie – Stone doesn’t look too good. He’s worried Stone might pass out and release the switch, so it’s up to him and the other cop to take him down. When Stone is distracted by his inhaler, the two pounce and manage to take him down and secure the dead man’s switch with a shoelace. Espo calls Ryan to tell him it’s all over, but it’s not over yet. The CDC found evidence of the missing flu virus in Stone’s apartment, and it’s H5N1. Stone definitely has the virus, and may have infected everyone on the train.

At the moment, the best theory Castle and Beckett have is that Stone stole the virus, and when Reeves found out he was killed. When they go to question Stone at the hospital, it turns out they couldn’t be more wrong. All Jared wanted was to free Erin from prison; he didn’t want to hurt anyone. Beckett doesn’t buy it; Stone had tickets to a seminar and the opera that evening which would have given him the opportunity to infect hundreds of the rich people Stone is so against. Stone insists that everything that has or would have happened was because of the planning of a guy he meant online. The mysterious character, who goes by White Knight, set everything up. Stone was just a pawn who didn’t even know he was sick. He just wanted his girlfriend back.

It turns out that Stone was deliberately infected; his asthma inhale was tampered in order to give him the H5N1 virus. The answers have to lie in Paul Reeves’ investigation of the missing vaccine. As Castle and Beckett look into his files, they discover that millions of the H5N1 vaccine were ordered, even thoug there were only 1000 cases of the flu reported globally. It’s as though someone knew there was going to be an outbreak.

They bring Paul Reeves’ boss, Ms. Jarvis, into the precinct. She had recently put all of her assets into stock for the lab that makes the vaccine, and after looking into her cloud account, the detectives found emails signed by White Knight. Paul was one of the prosecutors who put Erin Wilson away, and knowing Jared Stone would do anything to get his girlfriend back, he became the perfect fall guy for her plan. When Paul’s investigation got too close, she got Jared to set up a meeting for her, so she could get him off her trail.

As Esposito leaves the hospital, the traffic cop from the subway comes to visit him. In the moments before they jumped on Stone, Espo uttered Lanie’s name, and she wanted to tell him that if he’s thinking of her during near death experiences, she’s got to be something special. So when he gets back to the precinct and sees Lanie again, she gets a really big … hug. I guess it’s a start.

That was intense. Even though the possibility of Esposito getting killed off is pretty slim, it didn’t take the intensity of the situation away at all. Having the hostage situation play out juxtaposition to the Reeves’ murder investigation was an excellent plot device. Just when you think you’ve got one thing figured out for the case, something would happened with Stone completely changing everything. It was very effective and made for a great mystery. I thoroughly enjoyed it.