In the Fairy Tale past Snow White decides to hunt down Medusa on her honeymoon in order to stop Regina. When she tries to take Medusa's head, it backfires and Charming is turned to stone.
Snow realizes that her own paranoia has ruined her happiness more than Regina. She uses Medusa's own reflection to turn her to stone and free's Charming.
In Storybrooke, the crew from Neverland is welcomed back but no one realizes that Henry is really Peter Pan. Pan has his shadow kill the Blue Fairy and Regina brings him to her vault to protect him. Pan (as Henry) knocks her out and then steals the original curse.
In trying to stop Pan, Emma takes him out of Pandora's box only to find out it is really Henry. When everyone rushes to the vault they realize that Pan plans to unleash the curse on Storybrooke once again and this time their won't be a savior to break it.