ABC has released an official description for the Once Upon A Time episode "The Heart Is A Lonely Hunter."
Images from the episode can be found here.
KSiteTV has gotten clarification that this is the episode airing on December 11.
"The Heart is a Lonely Hunter" - One of the town's residents begins to remember their fairytale past, and Storybrooke mourns the loss of one of their own. Meanwhile, in the fairytale world that was, the Evil Queen attempts to find a heartless assassin to murder Snow White.