Directors include Justin Molotnikov, Ashley Way, Alice Troughton and Declan O'Dwyer.

Alexander Vlahos became part of the regular cast in this series and John Hurt returned as the voice of the Dragon.

Supporting cast members include Adetomiwa Edun, Eoin Macken, Tom Hopper, and Rupert Young.

For the new arrival is the sorcerer Mordred, the Druid boy whose destiny it is to end the King's life and bring chaos to Camelot; after all, Merlin has been warned in the past that Mordred is destined to unite with the evil Morgana in a deadly alliance which will destroy Camelot.

With the death song of King Uther haunting the castle, Morgana's powers greater and more dangerous than ever and Guinevere crossing over to the dark side, both Merlin and Arthur find that their destinies are approaching.