ABC will air "Once Upon A Time: Secrets of Storybrooke", a one-hour special that pulls back the curtain and takes viewers behind the lights and cameras to the fantastical worlds of the series, now in its fourth season. Narrated by series regular Jennifer Morrison who plays "Emma Swan", the program will let viewers find out just what it takes to flip our most beloved fairytale memories on their head, from the writers, the actors and artists who really do make magic happen every day. Secrets about the show's visual effects, how costumes help shape a character and how a small town outside of Vancouver is transformed into Storybrooke will be revealed.

David and Mary Margaret suspect Cruella and Ursula have come to Storybrooke looking for something more than their own happy endings - something that threatens to reveal a secret they thought was long buried. Emma begins her own investigation of Cruella and Ursula, but she can't shake the feeling that her friends and family are keeping something from her. Regina and Henry continue their search for the Author, turning to Pinocchio and Marco in the hope Pinocchio might remember a clue that will help them. Meanwhile, in a flashback to Fairy Tale Land, Snow and Charming cross paths with the Queens of Darkness as the threat of the Evil Queen's Dark Curse hangs over all of them.