A refreshing break from the heavier opening to this season of Merlin, we start off episode three with Merlin in the library searching for a book Gaius needs for some research. He heads off to the east wing where he spots the bestiary on the topmost shelf of a cobweb covered bookcase. In doing so, he steps on a lower shelf and activates a hidden switch, spinning the wall around to a very forgotten and dirty room. While checking out the room, Merlin bumps a container on the floor and groaning is heard from inside. Merlin uses magic to loosen the lock and frees a goblin.
Dumbfounded, Merlin tries to keep the goblin quiet so as not to draw attention to them and get the creature back inside the box. The goblin pretends to go along with it, but he is a mischievous one and runs off, destroying vases and overturning furniture left and right. Merlin chases after him and eventually finds the goblin in Arthur’s room making a complete mess of everything. Arthur walks in as Merlin is on his hands and knees trying to find the goblin, and Merlin attempts to cover up the truth claiming to have begun spring cleaning. The goblin uses this opportunity to slip out of the room, but not exactly quietly. He then runs into Morgana’s room and makes a mess of her jewelry, obviously looking for something.
He goes to Gaius to find out more about the creature and Gaius informs Merlin that the goblin is only after one thing – gold. The goblin will do whatever it takes to get his hands on as much gold as he possibly can. However, that’s not all the goblin is up to. He begins to play tricks on the people of Camelot, starting with Uther who suddenly finds himself without any hair. Before he can cause too many problems, Gaius and his student plan to trap the goblin luring it out with gold, which Merlin “borrows” from Arthur without the prince’s knowledge. Unfortunately, their plan fails as the goblin transforms into a wisp and pops himself into Gaius’ head. Merlin doesn’t notice though, and continues searching for the goblin.
Gaius begins to act strangely and Merlin is becoming suspicious of what really happened. It starts when Goblin Gaius decides to visit the tavern where he witnesses the soldiers arm wrestling for gold coins. He gets in on that action and walks away with a handful of gold. Merlin deals with the physician in the morning who is nursing a hangover. Morgana visits Goblin Gaius while Merlin is out complaining of a poor night’s sleep and missing her healing bracelet. After telling Morgana that he can see the evil inside her, he hands her a sleeping draught then deals with a husband and wife he easily manipulates for coin by charging for cures, something Gaius never does. After selling to the couple, Goblin Gaius takes his potions out to the common people of Camelot, making up symptoms so he can sell his “cures”. One of his unlucky targets is Gwen, who he convinces has caught a virus that will strike her mute and covered in boils. He goes back to the scene of his first crime, giving Uther an elixir to aid in the regrowth of the king’s hair, slapping it all over Uther’s head. Back in his rooms, Goblin Gaius pulls out a chest of gold and starts licking it all over. Merlin catches him in the act and warns him to get out of Gaius. The goblin refuses, reminding him that as long as he is inside Gaius Merlin would dare not hurt him.
Because of all the vandalism around the castle, Arthur gives a report to his bald father in the counsel room as to the status of the investigations. Merlin, Goblin Gaius, Gwen and Morgana are also in attendance and it seems the potions that the goblin has been handing out have some smelly side effects. Gwen, Morgana and Uther all have uncontrollable flatulence and flee the room as soon as Uther dismisses the meeting. It seems Goblin Gaius is having too much fun at the expense of everyone.
In order to keep up the charade, Goblin Gaius plants a book of magic in Merlin’s room and blames the warlock for the tricks that have been taking place. No one believes Merlin when he denounces Gaius as being possessed by a goblin and is sentenced to death. At night, he sneaks out of the jail and hides at Gwen’s where he convinces her to help him capture the goblin and save Gaius. Meanwhile, Arthur is also becoming suspicious of Goblin Gaius and confronts him about it. Gwen heads to Arthur’s rooms to seek his help with clearing Merlin’s name where she finds him hiding behind his bed, with a set of fuzzy donkey ears and only able to communicate braying like a donkey.
(I had to share the video clip, because a screenshot just cannot do this scene justice.)
Now that Arthur can confirm that Gaius is indeed possessed by a goblin, Merlin can put his plan into action. He heads back to the library to retrieve the box he found the goblin in and prepares a poison to give Goblin Gaius. He coats the gold in the goblin’s chest with the poison and waits for it to sense danger, thus forcing him to leave Gaius’ body. Once he jumps out of Gaius, there is a scuffle in the room which leads to Gwen dropping the antidote and it getting mixed up with other potions. The goblin tries to enter Merlin the same way he did Gaius, but Merlin keeps him trapped in his mouth until he is able to spit him back into the box he found him in. Gwen and Merlin frantically try to find the potion for Gaius, doing so at almost the very last minute.
Gaius saved and back to normal, Uther hears most of the truth and pardons Merlin. All seems to be back to normal, but Morgana seems a bit suspicious of Merlin. Gwen and Arthur promise to pretend that nothing happened to them during the whole ordeal. But Merlin leaves one bit of magic in place, just for one more day.