Mark shares the story behind Camelot Unchained in update #27. Some very interesting information.
"In this update I talk about the Piercing of the Veil, the Veilstorms, the three swords, the anvil and many (not all) of the events that precede the main story line for Camelot Unchained. I hope you enjoy it."
Go over here for his video lore update: CU Lore Vid