Buried Home (BBC Merlin)

Cyra has grown up all her life alone in a Druid camp after her parents were killed during the Great Purge, learning to live like an outsider, and using people for her own gain.
Meanwhile, witch, Arietta Goodwin, has lived life with servants at hand, the best food and the best room, all because her parents had ties in with King Uther Pendragon of Camelot, yet has been living in fear that one day she will be caught and killed for her magic which she sees as a curse.
When the two girls form an unlikely friendship, Cyra tries to force Arietta into using the magic she has vowed never to use. Only when Morgana Pendragon sets a seige onto Camelot, a spell is cast and they are taken to a world where they would have never imagined - when Camelot is seen as only myth and legend, and it seems they have no way back.
And as Morgana too ends up transported to 1970's Britain, the three meet face to face. Can Arietta face her fears as her magic finally strengthen, and Cyra's loyalty is tested on whether to stay with her best friend protecting Camelot, or to fight against it - to gain freedom - with Morgana.