Either way, it's going to be one heck of a reunion when Emma finds her long lost friend and tells her the identity of her mother. "Lily" is the 20th episode of Once Upon a Time's fourth season.

Will Regina be by Emma's side as she searches for Lily or will she be off warning Robin Hood that his wife is really the Wicked Witch?

But will the search for answers about Lily push Emma even closer to the dark side?

Emma and Regina prepare to leave Storybrooke to find Maleficent's daughter and warn Robin Hood about Zelena on Once Upon a Time.