‘Once Upon A Time’ Season 4 Latest News and Spoilers: Will Storybrooke's Savior Emma Swan Finally Take a “Walk on the Dark Side”?

ABC's Once Upon A Time season 4's next episode is set to air on Sunday, March 1, at its 8:00 pm time slot. Marking the start of the second half of the show, episode 13 titled "Darkness on the Edge of Town," directed by Jon Amiel from a script written by showrunners Edward Kitsis and Adam Horowitz, will have the Queens of Darkness - Maleficent (Kristen Bauer van Straten), Cruella de Vil (Victoria Smurfit), and Ursula (Merrin Dungey) - gathering and on their way to Storybrooke.

In the teaser clip for the episode, now available on the Internet, Rumple (Robert Carlyle) says: "For Cruella, Ursula, and Maleficent to obtain their happy endings, they must find someone whose soul can be molded, one whose heart is brimming with blackness, who is ready to walk on the dark side." Then the scene shifts its focus to Emma (Jennifer Morrison), who is seen in the midst of the Queens of Darkness with an evil smirk on her face.

In an interview with TV Guide, Kitsis said about Emma: "She's about to find out some really bad information." Elaborating, Horowitz added: "One of the big themes in the second half of the season that we want to deal with is what makes someone a hero and what makes someone a villain. What the differences are and what the common ground is. Emma has spent a long time in the series being told she's a Savior, being told she's a hero. Now she's going to have to face that it's not as black and white as that. Going into the second half of the season, all of our characters are going to be wrestling with this idea of good and evil, not just in terms of what they're facing as an external threat, but internally within themselves."