The fourth series of Merlin comes to an epic conclusion on Christmas Eve with The Sword in the Stone: Part 2.

Morgana and Helios have successfully captured Camelot, and Merlin and Arthur are outlaws on the run. Trapped in Ealdor with a ruthless army closing in, their situation becomes desperate. Arthur must take control before Camelot is lost forever… But faced with Agravaine’s betrayal and the strength of Morgana’s force, the young King has lost his conviction. Only Merlin can restore his faith, and only an extraordinary act can prove to the King that he was born to rule. Will the young warlock convince Arthur before his dreams of Albion fall to pieces?

Trailer:

The Sword in the Stone: Part 2 airs 24 December at 8pm on BBC1