Oh, Nikki, You're So Fine
In Tick, Tick, Tickâ€¦
, Castle and Beckett cross paths with a clever killer obsessed with Nikki Heat. FBI Agent Jordan Shaw is impressed as Castle cracks the murderer's numerically-coded message when he realizes the digits are actually page numbers from Heat Wave. Castle later impresses Beckett when he doesn't immediately gloat about breaking down her front door after the killer blows up her apartment.