Showtime's Penny Dreadful got an "extraordinarily famous" visitor on set on Thursday.

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Director James Hawes returned to Dublin for production on Wednesday and hit the ground running as the Victorian supernatural drama filmed some new scenes the very next day. With all the hard work cast and crew put into the series, Hawes teased a special guest on Twitter Thursday that kept fans guessing.

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Some fans thought perhaps the director was referring to legendary Broadway star Patti LuPone, who joined the Showtime series this year as part of the season 2 cast. Hawes' third clue, however, knocked LuPone out of the running as he confirmed that this guest was not part of the show's cast.

Other guesses included members of the Rolling Stones and Sting. Hawes ultimately decided to keep the identity of this star under wraps for now, though he's promised to try to snag a selfie when the visitor returned later in the week.

Penny Dreadful returns on Showtime for its second season in 2015.

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