When the murder of an Army veteran puts Beckett on the trail of the man who shot her, Castle must decide how much he's willing to sacrifice to keep her safe. As secrets are revealed and feelings are put on the table, the lives of the detectives at the 12th Precinct may never be the same.
Castle (to Beckett in her apartment): Because of everything that we have been through together. Four years, I’ve been right here! Four years just waiting for you to just open your eyes and see that I am right here. And that I’m more than a partner.
Beckett (to Castle): I almost died and all I could think about was you. I just want you.
Castle (to Beckett): Every morning I bring you a cup of coffee, just so I can see a smile on your face. Because I think you are the most remarkable, maddening, challenging, frustrating, person I've ever met. And I love you Kate, and if that means anything to you, if you care about me at all, just don't do this.
Gaffe: In previous episodes, it was established that Montgomery's children were two daughters. In the family photo shown, though, a daughter and a son are shown.
Johanna Beckett's tombstone reads, "vincit omnia veritas" ("truth conquers all").
Castle traditionally spends Memorial Day weekend at his house in the Hamptons. This year, Alexis is graduating and Martha is going alone. It's unclear what Castle's original plans were other than to view the John Woo movies; even the WriteRCastle twitter feed had mentioned that he would be going.
Although Esposito is furious with Ryan for calling in backup, this was precisely what he and Beckett were about to do themselves when they were jumped.
This episode has numerous references to previous episodes:
Beckett uses the same interrogation tactic as Agent Fallon in Setup: threatening to take away a woman's children if she doesn't waive her right to remain silent.
The argument between Beckett and Castle is similar to the argument they have in "Knockout". In both cases, Castle urges Beckett to stop investigating and the relationship is broken off. Unlike the last time, though, it is Castle who makes the decision to call things off.
Cole Maddox beating her so easily, despite the fact that she had a gun and he did not, was foreshadowed in Pandora, where CIA operative Thomas Gage was equally casual about defeating her in similar circumstances. Actress Stana Katic later said in an interview that the fight was intentionally one-sided, as a metaphor for how powerless she is against the all-powerful conspiracy.
Her inability to climb back up onto the roof after the fight with Maddox was foreshadowed in Kill Shot, where she was unable to climb a ladder to the roof due to the injuries sustained in Knockout.
While Mr. Smith warns Castle to restrain Beckett, no one outside the precinct was aware that she was working the investigation or had connected it to her mother's murder. Maddox's parting line that they "know exactly who they're dealing with" could be taken as an admission that there is a mole within the 12th precinct.
The purpose of the burglary at Captain Montgomery's house was not to remove any lingering evidence, it was to identify "Mr. Smith" so that he could be neutralized and Beckett safely assassinated. Cole's parting line could also be a reference to this mission: to identify the man who's been protecting Beckett.
Watch for: under the wedding photo that Cole uses to identify Smith is a legal document, a series of witness statements regarding a crime.
This is the first time that Castle and Beckett kiss "for real", not undercover. Executive Producer Andrew Marlowe has since confirmed that things proceeded exactly as the show implies: that the two did in fact sleep together.
Although this episode finally brings Castle and Beckett together romantically, there are two caveats. As always, Beckett makes her move only once Castle has totally given up and broken off the relationship. Second, Beckett still hasn't told Castle that she loves him.