"Once Upon A Time" revealed a shocking twist that was most unexpected: Snow and Charming have a dark spot in their heart as they are responsible for Maleficent's child's death. No wonder she wants revenge.

Season four's forthcoming episodes will delve deep into this particular story arc. Co-creator Adam Horowitz told TVGuide that fans will learn how the baby died, what part Snow White and Prince Charming played and provide insight into the pain she still feels with the loss of her dragon-child. He elucidated, "You will learn how it's made and how she gets it. What we're going to see is the critical juncture of how the baby is born and what comes a bit after it's born. We're going to obviously explore how she lost her child. And at that end of that episode, I think you can see on her face that it was a very painful experience."

The episode's synopsis states that Regina will go undercover in "Enter The Dragon" for Snow and Charming in order to find out what the Queens of Darkness are up to. While she hangs out with them in order to learn of their schemes, can the once Evil Queen resist the temptation of going over to the dark side? Audiences certainly hope she can. As the season progresses, viewers will understand the source of Maleficent's pain as the series will frequently flashback to when Snow, Charming and Maleficent were living in the Enchanted Forest.

Interestingly, episode 15 will also reveal what Hook did to Ursula. While most viewers may think it's sexual, Edward Kitsis, the show's other creator, clarifies that it isn't sexual but soul-crushing. Fans will see the origin of Ursula and what soul-crushing thing Hook did to her.

The creators also teased that Maleficent's baby's father will also be explained, according to to TVLine. Moreover, glimpses of Will Scarlett and Robin Hood's past will also be provided.

Season 4 episode 15 airs on Sunday, March 15 at 8 p.m. on ABC.