Mondays 10:00 PM on ABC
Castle
Looking to watch Castle Season 4 Episode 21 online? TV Fanatic is your destination for every paid and free streaming option of the Castle S4E21 full episode from 2 affiliates.

Rating: 4.6 / 5.0 (283 Votes)

Episode Details

Castle Season 4 Episode 21: "Headhunters"

It's a Firefly reunion on Castle this week, as Adam Baldwin guest stars in the fun role of Detective Ethan Slaughter.

Castle Season 4 Episode 21 Quotes

Forget severed heads, I want to meet that guy!

Castle

Martha: Playing with dolls, are we?
Castle: They are action figures.

x Close Ad