The Stable Boy

"The Stable Boy" is the 18th episode of Once Upon a Time.

Summary
Emma continues her exhaustive search for evidence that will prove Mary Margaret's innocence in the murder of David's wife, Kathryn. Meanwhile, in the fairytale land that was and before evil blackened her soul, Regina must choose between betraying her mother, Cora, and marrying for true love, or betrothing royalty and living a regal - but loveless - life.