Most fairy tales start with the phrase "once upon a time" and ends with "happily ever after." But for fans of the ABC show, the happy ending will have to wait as the storyline for season five appears to be darker than ever before.

"Once Upon a Time's" heroine is now its greatest villain as Jennifer Morrison (Emma Swan) is transformed into the Dark One. The show's official poster for the San Diego Comic-Con does show a very different look for Emma — snow white face, blood red lips and black feathers where her eyes are supposed to be.  

The first episode of season five will pick up where last season's finale left off, with Emma transformed into the new Dark One after evil spirits left Rumplestiltskin's body. Incidentally, Robert Carlyle's Rumple is still alive but in stasis. How long he will remain alive is something that viewers will discover next season. Luckily for fans of the series, the actor's name is still on the casting list so it is guaranteed that he will be back.

The show will be introducing some well-known Arthurian characters next season — King Arthur, Guinevere and Merlin —and the network is currently looking for actors who can play them. Merlin, who is expected to be the one to free Emma from the darkness, is described as someone who always puts duty first. The network is looking for a black actor with a distinct British accent to play him. However, the casting call for Guinevere is for a Latina in her mid-20s to mid-30s. The role of King Arthur has reportedly gone to Liam Garrigan of "24: Live another Day."

Storybrooke residents Hook (Colin O'Donoghue), Snow (Ginnifer Goodwin), Prince Charming (Josh Dallas) and Henry (Jared S. Gilmore) will be scrambling to turn Emma back to normal. Other residents who are also sticking around are the Wicked Witch (Rebecca Mader) and Robin Hood (Sean Maguire).

"Once Upon a Time" is set to return to ABC on September 27.