The clip, over two minutes long, offers new footage from the season as well as a glimpse into the world's bleak future if Green's character Vanessa Ives doesn't stop the "end of days."
The conflicted protagonist also reveals she is being hunted by a being who has sought her "since the dawn of time."
The forthcoming season of Penny Dreadful will see the return of Tony Award-winning actress Patti LuPone as Dr. Seward, a therapist who treats Ives' character. Actor Wes Studi also joins the series as a regular alongside Hartnett and Dalton's characters.
Shazard Latif will portray Dr. Henry Jekyll in the much-anticipated third season, which will also include guest appearances by Christian Camargo, Sam Barnett, Jessica Barden and Perdita Weeks, according to ComingSoon.net.
Season 3 of Penny Dreadful returns to Showtime May 1.