The Lady of the Lake (S02E09)

When Merlin discovers the beautiful druid girl Freya trapped in a bounty hunter's cage, he knows he must help her escape. Gaius warns against getting involved, but Merlin refuses to listen, harbouring Freya in the tunnels beneath Camelot. But with the bounty hunter searching for his missing prize and a ferocious magical beast on the loose, Freya cannot stay hidden for long. Merlin's intense new friendship is tested to the limit, and he is forced to make some heartbreaking decisions as he battles to keep Freya safe. (BBC)