So, in the build-up to Merlin series 4, it's likely that we're going to see a few episode titles before the series begins (this isn't confirmed, last year the titles were revealed by the Radio Times 13 days before broadcast.) So far, we've got the title of the opening two-parter (Revival of the Witch) and it looks like another title has come out. So, here's the alleged title for series 4 episode 3:
AN UNCLE AND AN ENEMY.
It's from Merlin Wiki, not the most reliable source, so we can take this with a pinch of salt.