Credit: Randy Holmes/ABC Television Group © 2011 Disney Photo: Castle and Beckett in Season 4, Episode 9: “Kill Shot”

Tonight's episode of Castle was the one we've been waiting for all season.

After months of pretending like nothing was wrong, Detective Kate Beckett came face-to-face with her PTSD, triggered by a crazy sniper terrorizing the streets of New York City.

Surprisingly, it wasn't Richard Castle who came to her rescue — it was Detective Esposito, played by Jon Huertas, who gave Kate the wherewithal to turn her pain into power. Like his character, Jon served in the U.S. army for eight years, an experience that undoubtedly helped make his performance all that more convincing.

But it was Stana Katic's gut-wrenching, tear-jerking performance that stole the show. She took us on an emotional journey through Beckett's downward tailspin, leaving our palms sweating and our hearts pounding. We always knew Stana could act, but this performance exceeded every expectation. Emmy anyone?

As for Castle, we didn't see much of our favorite writer-turned-cop, but his presence was palpable. When Beckett confessed to her therapist that she's ready to change, ready to make peace with her scars — from both her mother's murder as well as her shooting — it was as if the fog lifted and the clouds parted.

The winds of change are blowing through the 12th precinct, and they're taking Beckett's wall down with them.