'Castle' casting: Raphael Sbarge of 'Once Upon a Time' will guest-star

Is "Castle" going to have a crisis of conscience about anything in the near future? If so, the show is in luck -- Raphael Sbarge, who played Archie/Jiminy Cricket on "Once Upon a Time," will make a guest-starring appearance on the mystery show.

The news first came from Sbarge himself, who tweeted photos from the show's set. The first such photo appeared on Friday (March 15), featuring a chair and the hash-tag "#GuessWhereIAm. In case people were not immediately sure of what show he was at, Sbarge followed up with a photo of himself and "Castle" star Nathan Fillion:

What is Sbarge doing on "Castle"? Give Me My Remote reports that the actors guest role will be as a Dr. Darrell Meeks, appearing in some capacity on the 20th episode of "Castle" Season 5. Per yet another tweet from Sbarge, the episode will be directed by Jonathan Frakes ("Star Trek: The Next Generation").

Everything else remains a mystery, at least until Sbarge tweets the solution.

"Castle" airs Mondays at 10pm while "Once Upon a Time" airs Sundays at 8pm. Both shows are on ABC.