The title of this episode, which also served as the overall title for the final season, is taken from from the Lord Of the Rings, in which Frodo tells Sam "There is no veil between me and the wheel of fire."
In ancient Greek mythology, Ixion was bound to a firey wheel as punishment for offending Zeus. In ancient Greek theatre tragedy always arose from one initial misdeed; the wheel of fire was the inevitable progression from that first mistake to the final doom. Shakespeare's King Lear (Act 4, Scene 7) says he is bound upon a wheel of fire.
This takes place from August 19 to August 21, 2262.