S1, E11: When Arthur kills a unicorn while out on a hunting trip, a curse descends on Camelot. Could this be the end for the mythic city? An upset Merlin rushes to the animal's side as the knights cheer Arthur for killing this most highly prized of beasts. As the unicorn dies, Merlin sees a wizened old man watching the scene amongst the trees. Their eyes meet and then he disappears. The next morning, Arthur and Uther survey a valley in which the crops in the fields below have died overnight. It's the same story all over the kingdom. If they don't do something, the people will starve. When, later that day, the water in Camelot's well turns into sand, Arthur and Uther become desperate – the town is now facing a famine and a drought. Gaius suggests that these events cannot be a coincidence and that a curse has come to Camelot. That night, Merlin and Arthur are on patrol when they come across a strange man – it's the same person Merlin saw in the forest. He introduces himself as Anhora, the keeper of the unicorns. Anhora tells them Arthur is responsible for the curse, revealing it was unleashed when Arthur killed the unicorn. Arthur doesn't accept this and is angry at the suggestion he is responsible. Before he disappears again, Anhora tells Arthur that he will be tested and, until he has made amends for his actions, Camelot will be damned.