The warlock teenager Merlin is sent to Camelot, to lead better life, by his mother. He discovers the Great Dragon who told him that his destiny is to save the young Prince Arthur. He comes to know that the King Uther Pendragon has banned the magic. If anybody found doing so will be punished with death penalty.

Camelot holds it’s yearly sword tournament. Knight Armed usies a magical shield and is determined to win at any cost. Merlin is determined to prove that Valiant is cheating before Arthur is killed in a dual with him.

The water supply in Camelot gets poisoned by the sorceress, Nimueh and a plague spreads. Evil magic is considered to be the cause for this plague. Gwen's father suffer from this disease. Gwen is blamed for this witchery and is punished to death. Merlin and Gaius are trying their best to find a cure for this epidemic. Merlin, Arthur and Morgana investigate to find the real culprit in order to save Gwen from the punishment.

Nimueh returns and she tricks Merlin into consuming some poison from a chalice and he becomes very ill. Arthur attempts to find an antidote but ends up walking into a trap set by Nimueh.

In this episode 05 of Merlin Season 01, Lancelot comes to the Kingdom of Camelot. He saves Merlin's life from a winged monster who attacks Merlin. Merlin wants that the Lancelot should become a Knight of Camelot although he does not belong to a noble race. Unfortunately, Lancelot is send to the prison.

Edwin Muirden, a new physician of the court is able to find a cure for the mysterious sickness and he save the life of Lady Morgana. Where as Gaius fails to find remedy for this unknown illness. He is worried as the King Uther will be impressed by Edwin and Gaius will lost his job. He asked his friend Geoffrey of Monmouth to collect information about Edwin.

Lady Morgana sees Arthur being killed by a beautiful girl in her dreams. So she told Arthur to be careful. But Arthur's gallantry puts him in trouble when he jumps to save Sophia and his old father named Aulfric. They all come back to Camelot and Sophia starts using her womanly charm to attract Arthur. Merlin notices this and tries to know more and more about them.

A person who is a priest been caught with his son Mordred, by the guards of the king Uther. Morgana and Merlin saved the boy but the druid is caught and punished with death penalty. Morgana and Merlin come closer while helping that boy. The king passes out the orders that anybody who will help that boy will be executed.

Nimueh is back with her evil schemes to take revenge from the king Uther. She re-alive a dead Black Knight who disrupts Arthur's coming of age ceremony by inviting all the knights of Camelot to compete with him to death. Number of knights fight and die. This makes Arthur angry. It is soon very clear that Uther's past is haunting him.

A bandit, Kanan, and his men attacked Merlin's village, Ealdor. He wants to take off their land or he will kill the villagers. Merlin goes there to help his mother and other villagers along with Arthur, Morgana and Gwen. Merlin can use his magical powers to save everyone from that bandit but if he do so, he will lost Arthur's friendship.

Everybody cheers except Merlin when Arthur kills a unicorn while they are out for hunting trip. Because of the death of a unicorn which is the most respected animal, the Kingdom of Camelot is stroke by a curse. It is expected that this may be the end of this city. In order to save Camelot, Arthur has to clear some tests of Anhora who is the care taker of the unicorns.

In this episode 12, a sorcerer is helped by Gwen's father, Tom, in order to practice a magic in which the sorcerer converts lead into gold. Morgana and Merlin requested the King Uther and tell him that Tom is innocent. But the King is not ready to agree and pass out the order of death penalty for Tom.

When Merlin, Arthur and Gaius go out for hunting where they meet a furious beast who if bites anybody will die. It is brought up by old black magical powers. The person who is bitten by this beast can be saved by the old magic only. Arthur attacks the beast but the beast bites him. Merlin tries to save the future king i. e Arthur and for this he has to pay some price.