"Lily" is the nineteenth episode of the fourth season of the American fantasy drama series Once Upon a Time, which aired on April 26, 2015. When Emma Swan discovers that a former friend from her past, Lily, is Maleficent's long lost daughter, she embarks on a quest to find her and bring her back to Storybrooke in order to reunite her with Maleficent, and Regina teams up with her in an effort to warn Robin Hood about Zelena, but the two are about to face what awaits them outside Storybrooke. Inside Storybrooke, Gold finds himself dealing with Belle, and back in Emma's past, her friendship with Lily after she is placed in a foster home could threaten their future.