Merlin Season 3 Episode 10

When Morgana is tormented by dreams in which Guinevere becomes Queen of Camelot, Morgause encourages her to reveal Arthur and Gwen's courtship to Uther in the knowledge that he will do whatever it takes to stop his son from marrying a serving girl. As a result, Uther banishes Gwen from the kingdom forcing Arthur to make the ultimate sacrifice of leaving Camelot with her. Determined to stop the loving couple, Morgana frames Gwen for the scandalous crime of enchanting the Prince. With destiny once again at stake, Merlin will be compelled to risk everything to save Gwen from a gruesome death.