Merlin: Season 2, Episode 4

2 - 4: Lancelot and Guinevere

Gwen is accidentally mistaken for Morgana and is kidnapped by Hengist, a savage outlaw. Uther refuses to pay any money for her return, so Arthur enters Hengist's territory with Merlin in tow to rescue her. But Arthur is not alone, as he finds that Lancelot is also out to save her.