Episode Description: Beware, spoilers! To read - hover over the text.
On the hunt Arthur accidentally kills a unicorn, to which the anchor channel - the Keeper of the unicorns send Camelot a curse. And the next day all the crops died and the water turned to sand. Merlin and Arthur go to the elder, who offers Arthur to withstand a series of tests. Not all turned out at Arthur, but in the end he did. The last I had to bury the horn of a unicorn in a clearing, to give back to the elder and his mentee.