Beckett wants to keep this investigation between the immediate team only. Ryan doesn't feel right about this. Castle isn't thrilled either, especially after getting a call from the mystery man who warned him to keep Beckett away from her mom's case. As for the current case, Beckett learns that Orlando was hired by someone from his military days. Someone dangerous. They met at a church where surveillance footage provides an image of the man the team seeks.
Esposito sees that the suspect was holding a keychain from a rental company. Beckett wants to follow this lead, but Castle wants her to stop. He tells her why. Castle spills the news about how Montgomery's friend struck a deal to keep Beckett safe. He's been trying to keep her safe, too. Beckett is angry that Castle kept this from her. She wants to know how he could do this. It's because he loves her. This is something she's known for about a year.
Castle finally lets out all the things he's been holding back for so long. He says, "Four years I've been right here. Four years just waiting for you to just open your eyes to see that I'm right here. And that I'm more than a partner. 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."
Castle's heartfelt speech doesn't stop Beckett from wanting to go after the people who shot her. That's not something he can watch happen. Castle tells Beckett it's over. He's done. As for the case, the now-undermanned team learns that the shooter is going by the name Cole Maddox. They track his car to a location. Ryan's desire to assemble backup is quashed as Beckett and Esposito head to the scene. He dials Castle's number, but the call goes unanswered.