S9·E21 King of the Damned

Episode recap

Topic: Supernatural S9E21 (King of the Damned) episode recap.
Constraints:
Write ONLY verifiable facts from the provided SYNOPSIS and SOURCES.
No inventing/guessing titles, names, dates, counts, awards, ratings, etc.
Original, neutral, encyclopedic prose.
Plain text only (no markdown, no asterisks, no headings, no bullet points).
Word count: 280-380 words.
If the synopsis is sparse, stay concise rather than guessing.
TMDB Episode Synopsis: Abaddon gets leverage against Crowley to force him to lure the Winchesters into a trap. Castiel rallies his forces and asks Sam and Dean to help him interrogate a captive angel with ties to Metatron.
Series Sources:
Series title: Supernatural.
Created by: Eric Kripke.
Network: The WB and later The CW.
Run: September 13, 2005, to November 19, 2020 (15 seasons).
Main characters: Sam Winchester (Jared Padalecki) and Dean Winchester (Jensen Ackles).
Premise: Brothers hunting demons/paranormal evil.
The synopsis is very short.
The sources provide general series info but no specific plot details for S9E21 other than the synopsis provided.
Constraint Check: "If the synopsis is sparse, stay concise rather than guessing."
Constraint Check: "Write a grounded 280-380 word episode recap."
Conflict: The synopsis is only about 40 words. To reach 280-380 words without inventing facts or guessing is impossible if I strictly follow "Write ONLY verifiable facts that are explicitly supported by the provided SYNOPSIS and SOURCES."
Strategy: I must expand on the context provided by the sources (the series background) to reach the word count, while focusing the core of the text on the episode's specific plot points from the synopsis. I cannot invent plot points.
Drafting Content:
Introduction: Identify the series (Supernatural), creator (Eric Kripke), and the main characters (Sam and Dean Winchester, played by Jared Padalecki and Jensen Ackles). Mention the series' history (The WB/The CW, 2005-2020).
Episode Context: This is the twenty-first episode of the ninth season.
Episode Plot (from synopsis): Abaddon acquires leverage against Crowley. She uses this to force Crowley to lure the Winchesters into a trap. Meanwhile, Castiel is rallying his forces. Castiel asks Sam and Dean to assist him in interrogating a captive angel