|Starring:|| Colin Morgan|
|Producer:|| Johnny Capps|
|Broadcast:||November 7, 2009|
|Previous Story:||Beauty and the Beast|
|Following Story:||The Sins of the Father|
Uther is determined to wipe out magic in Camelot once and for all, and this time no one is beyond suspicion. He summons the most dreaded witchfinder in the land, Aredian, a terrifying man who will stop at nothing to uncover sorcery. Gaius impresses upon Merlin how much danger he is in, but Morgana needs no such warning. She is certain Aredian will see straight through her and she will be burnt at the stake. Can Merlin protect Morgana and Gaius without ending up in the flames himself?
While collecting wood, Merlin takes a break and amuses himself by shaping a distant column of smoke into a horse. Unfortunately, the horse is seen by a woman, and though Merlin denies having seen it, she insists it was magic at work and runs to tell the King.
Arthur offers to find the source of the magic, but Uther wants to use stronger measures, and sends for the Witchfinder. Gaius attempts to sway Uther into using alternative actions, but Uther remains firm in his decision. In their quarters, Gaius angrily reprimands Merlin for his carelessness and advises Merlin to hide everything which could link him to magic as the Witchfinder is a force to be reckoned with. The Witchfinder, a man named Aredian , arrives in Camelot shortly after. Morgana watches from her window, clearly fearing for her secret. Uther explains to Arthur that Aredian works for nobody and is a law unto himself and has been hunting sorcerers in foreign lands, before Aredian himself appears and states that Camelot stinks of sorcery. He also rejects the help of Arthur and his knights, favouring his own methods to root out the sorcerer and Uther agrees to pay his price for his help.
The next day, Aredian approaches Gaius in town and is introduced to Merlin. He requests Merlin's appearance in his chambers as he has some questions for him. During the questioning, Merlin denies having seen anything magical in the forest. Aredian remains unconvinced, but allows Merlin to leave, for now. Later, he brings three young women before the King, and they all testify to having witnessed acts of sorcery in Camelot. Merlin is named as a suspect, much to Arthur's disbelief. Merlin and Gaius have no choice but to let Aredian and his men search their home. The search is thorough and destructive, and finally, a magical bracelet is discovered in a pot. Aredian means to take it to the King as proof of Merlin's sorcery, but Gaius steps in and claims the bracelet is his.
Returning to the chambers, Merlin is shaken to find everything in disarray. Uther is shocked to find that Gaius still practices sorcery, while Aredian seems to be quietly triumphing. Gaius undergoes gruelling interrogation at Aredian's hands. He is refused basic needs like water until he agrees to confess, but Gaius continues to refuse. Merlin consults the Dragon, who tells him that if Merlin tries to confess to save Gaius, Aredian would simply burn them both. He then tells Merlin that he cannot help him because he doesn't know how to, and that he is sorry; leaving Merlin almost in tears.
During his interrogation, Gaius admits to have treated Morgana. When asked, Morgana admits that Gaius had treated her for nightmares. Aredian's interrogation of Morgana is short, but she is made to reveal that her nightmares have become worse and not better with treatment, and that she has no idea what is in the potion Gaius gives her, leaving Aredian free to draw the conclusion that Gaius is giving her nightmares. However, he also seems to be suspecting Morgana of being a seer, as his next action is to inform Gaius that Merlin and Morgana are his next two targets. Gaius makes a deal with Aredian, promising to confess to sorcery if Aredian will leave the two children alone.
In front of the King and the court, Gaius proclaims he is the sorcerer responsible for everything that has been happening in Camelot lately. He is sentenced to death the following morning. Angered, Merlin accuses Aredian of lying, only to be taken away by Arthur. Alone, Merlin tries fighting Arthur, but Arthur says that he isn't throwing him in jail, but breaking the law by letting Merlin see Gaius. Gaius states that he was trying to protect Merlin, but Merlin says the bracelet was not his, and so they realise Aredian must have set them up. Merlin becomes enthused with the drive to prove Gaius' innocence, but Gaius warns Merlin he may die if he tries to do so.
As Morgana watches Gaius' stake being assembled, Aredian appears and takes her away for questioning. Gwen rushes to Merlin to inform him about this and Merlin reveals to Gwen that Gaius was set up. He rushes off to prove Aredian's guilt by sneaking into his chambers and rummaging through his things. Aredian returns to find his cupboard open and becomes suspicious, but doesn't find anyone in his room; although Merlin is hiding underneath the bed.
Back in Gaius' quarters, Gwen and Merlin find an article which states that the petals from the flower Merlin found in Aredian's cupboard has the ability to produce hallucinations; meaning that the witnesses brought forward earlier were seeing visions and not actual events. Rushing into town, Gwen and Merlin go to a chemist who reveals that Aredian has given him Belladonna to sell to his customers, and threatened him with death if he did not comply. Merlin sneaks into Aredian's chambers while he is sleeping and performs some magic. On the morning of his execution, Gaius watches the sun rise. Gwen waits for Merlin to return while Aredian prepares for the day's event. Gaius is taken by the guards while Merlin prepares to go seek Arthur's help in delaying the execution. Gwen offers to go instead and they rush off.
In the city square, the people of Camelot gather to watch Gaius' execution. Arthur angrily demands that Aredian show Gaius some respect. As Gaius is placed at the stake, Gwen begs Arthur to stop the execution. Arthur is sorry but he states he cannot do anything as his father has already ordered the execution. Enraged, Gwen tells Arthur he can do the right thing and not re-enact past events by letting an innocent man die, referring to her own father's death. Gwen firmly tells Arthur to stop looking down at her as she knows she is a servant, but he should start wielding his powers as a Prince. Shocked and convinced, Arthur stops Aredian from lighting the pyre.Before Uther, Merlin presents his evidence against Aredian. The witnesses admit to buying the Belladonna from the chemist, who in turn admits he got it from Aredian. Aredian denies the claims, yet Arthur defends Merlin and via a glance at Gwen, suggests a search be conducted in Aredian's chambers. The search reveals a horde of amulets inside Aredian's cupboards and a store of Belladonna eyedrops, all conjured up by Merlin last night. Aredian maintains his innocence, until a toad jumps out of his mouth, another trick of Merlin's. To Uther, this is confirmation that he is the sorcerer, but when Arthur, Uther and the guards advance on him, Aredian takes Morgana hostage at knifepoint. Merlin uses his magic to make Aredian's knife burn red-hot. Aredian staggers back in pain, stumbles over a chest, and crashes backwards through a window, plummeting to his death.
With Aredian dead, Gaius is freed. He begins the long process of restoring his destroyed home. Uther approaches him and offers compensation for the broken furniture. He apologises to Gaius for suffering at Aredian's hands, but Gaius points out that he really suffered at Uther's hands, since Aredian was doing Uther's bidding. For the first time, Gaius stands up to Uther about his stance on magic, arguing that his fear of magic has robbed him of reason and that he is seeing enemies where none exist: Gaius also remarks that while he has not been the first to be wrongly accused in Uther's war on magic, not all have been as lucky as him. A visibly shocked Uther assures Gaius that every measure will be taken to ensure that this will not happen again.
Later, around the dinner table, Gaius and Merlin discuss the findings in Aredian's chambers. Gaius accuses Merlin of overdoing it, and Merlin (jokingly) promises to never save Gaius' life again. They laugh, relieved to have escaped death and discovery once again.
- Colin Morgan as Merlin
- Bradley James as Arthur
- Katie McGrath as Morgana
- Angel Coulby as Gwen
- Richard Wilson as Gaius
- Anthony Head as Uther Pendragon
- Charles Dance as Aredian
- Katie Foster-Barnes as Beatrice
- Samara Maclaren as Rowena
- Amanda Fairbank Hynes as Annis
- Victoria Finney as Cathryn
- David Sterne as The Apothecary
- One piece of Aredian's evidence is a woman seeing (later revealed to be a hallucination) a Goblin dancing in fiery coals. An actual Goblin would later appear in Goblin's Gold.
- Another 'witness' speaks of faces in a well (also revealed as a hallucination). But this also happens later, as Uther is driven crazy in Season 3. And it also was something that had occurred during the Great Purge, as Gaius tells Merlin.
- The third 'witness' speaks of toads jumping out of a man's mouth; while this, too is merely a hallucination, it becomes foreshadowing. Merlin uses the 'testimony' against Aredian, when he casts a spell to do just that.
- This episode marks the first appearance of the execution of being burned at the stake. [Though when Gwen was under accusation in Season 1, Uther implied she’d be burnt at the stake].
- When Gaius accuses Uther of seeing foes where there are friends and sorcerers where there are but servants, he actually ignores the fact that Merlin, Morgana and Gaius himself are indeed sorcerers and use magic secretly, thus proving Uther right.
- Ironically, Aredian was also right with his suspicions, and Morgana later turned out to be Uther's biggest enemy.