Supernatural is on the cusp of it's 200th episode, and the production gears have started turning for the upcoming milestone.

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The script is in and preparation has begun for the 200th episode, which will air as the fifth episode of season 10.

"Let the prep begin on episode 200!" tweeted co-executive producer Jim Michaels on Wednesday.

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When the episode does air, fans should be ready for an extremely meta - and slightly musical - story.

"I haven't had the chance to read it yet but I've heard it's almost similar to our "The Real Ghostbusters" episode. We're not at a convention but we're at a place where they're doing a play based on the Chuck Shurley books," explained Jared Padalecki (Sam), according to Zap2It. "So not only are these books based on our lives, now people are doing a play based on these books, and someone is haunting it, so we go and try to investigate what's going on at this play, based on the books about our lives."

Find out more when Supernatural returns to The CW on Oct. 7 at 9 p.m. ET. Click the video below to catch the final moments of season 9.