Season
Episode
- Episode 1: Rise
- Episode 2: Heroes & Villains
- Episode 3: Head Case
- Episode 4: Kick the Ballistics
- Episode 5: Eye of the Beholder
- Episode 6: Demons
- Episode 7: Cops & Robbers
- Episode 8: Heartbreak Hotel
- Episode 9: Kill Shot
- Episode 10: Cuffed
- Episode 11: Till Death Do Us Part
- Episode 12: Dial M for Mayor
- Episode 13: An Embarrassment of Bitches
- Episode 14: The Blue Butterfly
- Episode 15: Pandora (1)
- Episode 16: Linchpin (2)
- Episode 17: Once Upon a Crime
- Episode 18: A Dance with Death
- Episode 19: 47 Seconds
- Episode 20: The Limey
- Episode 21: Headhunters
- Episode 22: Undead Again
- Episode 23: Always
Castle Season 4 The Blue Butterfly
After a serial killer imitates the plots of his novels, successful mystery novelist Richard "Rick" Castle receives permission from the Mayor of New York City to tag along with an NYPD homicide investigation team for research purposes.
