After a couple of average episodes things improved significantly this week. The Crystal Cave was a very tense and atmospheric episode, though slow in parts and lacking any real action. Still, it helped push this season's theme of Morgana's fall and her plans to murder Uther.
Arthur and Merlin find themselves being chased into a wonderfully realised (and quite LotR-ish) Valley of the Fallen Kings. Arthur is shot by an arrow and lies near to death and Merlin is unable to help him. Luckily, a mysterious old man called Taliesin appears, heals Arthur and, whilst the prince sleeps, shows Merlin the crystal cave - the root of all magic. In here, Merlin sees various visions of the future, one of which shows Uther apparently being stabbed in his sleep by Morgana. Leaving the caves, Merlin and Arthur head back to Camelot where the young wizard finds out that Taliesin has been dead for many years and his future visions appear to be coming true!
Of course, Merlin tries to stop Morgana but finds that fate will not be thwarted. By the middle of the episode, it appears that he has succeeded in stopping - and in the process almost killing - Morgana (who actually wasn't out to kill Uther at that time) only to find that his actions lead to the murderous visions he had seen.
In this episode, we - and Morgana - discover that Uther is her father and not just her guardian. This explains why Uther has been so protective of, and concerned about, her this season. In fact, he is so desperate to ensure that she does not die in this episode that he even begs Gaius to use sorcerous means to heal her.
This, I felt, was a little out of character - Uther knows directly the dire consequences of using magic to keep another from dying (it's the reason he's so set against magic in the first place). Perhaps though, the fact that he abandons his own draconian rule when desperation looms, shows us that he inwardly knows that magic is not univerally evil. It also helps cement his vast love for Morgana, which I'm sure will play a further part in future episodes.
Overall, a very entertaining episode - close but perhaps not quite as good as the first story of this season - which gives me hope that Merlin can continue to deliver the goods. Unfortunately though, next week's trailer looks like we're in for another filler on Saturday.