Undercover to catch Lazarus, Beckett was discovered, tortured, and sent to be killed in the woods. She wasn't even supposed to be working drug operations. Near the end of Castle 6x17, "Belly of the Beast", this can be considered 6th Castle/Chuck crossover in the "Averages" series or 10th in the #CSvTNA series, which also includes Chuck-only stories.
Crossover - Chuck & Castle - Rated: T - English - Chapters: 1 - Words: 7,105 - Reviews: 5 - Favs: 9 - Follows: 5 - Published: 6/7/2021 - Chuck B., Sarah W., Carina, Kate B. - Complete