Storybrooke was originally part of a fairy-tale world. Once the curse was half-broken they all remembered, apart from Regena and Mr.Gold. Then, when Hook and Korra, the mother of Regena, came to Storybrooke. That was solved easily too. Mary Margret, or Snow White, is still growing darkness in her heart when Gold finds a way to bring them back to their own world; but there is something else. The spell he uses could either bring them to a new world - or a completely different one. Deciding to take the risk, the Blue Fairy, Regena, Charming, Snow, Emma, Henry and Gold go together to test it; and end up in a world beyond what they can understand.
WARNING; I am labeling this for everyone, because Once Upon a Time is a family series, but it contains mild swearing.
Also, if you dislike this, please leave a comment to tell me why so I can fix this, unless its the plot. Why would you click it and read it if the series doesn't interest you?