Esposito is held hostage on a subway train by a man linked to the death of a Government Accounting Office investigator.
Tropes that appear in this episode:
- Bait-and-Switch: Early in the episode, Esposito talks to Ryan about being ready to move forward in life, becoming a husband and father. At the end, Marisa (who he connected with about being former soldiers who became cops) reveals she lied about not having family, and has a five-year-old son. As Esposito looks stunned and we're thinking he's about to move on... Marisa asks, "Who's Lenny? Or is it Lanie?" She learned how to read lips after an IED blew out her ear drum and he was muttering Lanie's name under his breath before they took down Jared.Marisa: Who you think of in that moment is who matters to you. Don't trade something that's real for something that isn't.
- Call-Back:
- Early in, Castle goes through the duos that he's reminded of, now that he and Beckett are married, such as McMillan & Wife. Beckett mentions Turner and Hooch, and that Castle "still reminds [her] a little of Hooch", a reference to season 2 and the 2nd season opener.
- At the end of the episode is a mention of the Old Haunt, the bar that Castle bought near the beginning of the series.
- Camera Abuse: Jared shoots the camera in the subway car once he realizes it's there.
- Chekhov's Gun: Jared keeps sucking on his inhaler as he grows more ill. Turns out it's the virus delivery system, and the plan was for his asthma to kick in as he got nervous during the fake bombing.
- A Day in the Limelight/Lower-Deck Episode: A showcase episode for Esposito, with Lanie and tech Tory appearing in the entire episode. Even background character L.T. gets a minor "day" by leaving the precinct for once.
- Greed: Carol buys shares of a pharma company that makes vaccines for a deadly strain of flu and colludes with an executive of that company to have a sample of the flu stolen. She then has Jared infected and manipulates him into going to a crowded area to unwittingly spread the disease, thereby starting an epidemic which would justify the sale and use of the vaccines, allowing the company (and Carol) to profit immensely. When Paul stumbles onto the conspiracy during his investigations into the pharma company, she has him killed.
- He Knows Too Much: The victim, Paul, was a GAO investigator looking into suspiciously large orders of flu vaccines being made by a pharma company, which turn out to be related to a conspiracy to start a deadly flu epidemic. Fearing discovery of her role in the conspiracy, his supervisor Carol has him killed.
- Lame Pun Reaction: Castle makes some subway-related jokes and puns towards the end of the episode. Esposito and Lanie are not amused.
- The Plague: Turns out the guy who held up the subway was infected with a deadly virus...and it leads to the identity of the killer.
- Propping Up Their Patsy: Jared is a useful pawn for the real plan, which is to release a deadly plague. White Knight gave him a detailed plan and infected him.
