|First Aired:||25 September 2010|
|Written by:||Howard Overmann|
|Directed by:||Jeremy Webb|
|Guest Stars:||Michael Cronin (Recurring), Mark Williams (Voice), Duncan Meadows, Simon Nehan, Gemma Arrowsmith, Rupert Young (Recurring)|
|Filming locations:||Chateau de Pierrefonds|
Merlin stumbles across a secret chamber and accidentally releases a Goblin. The mischievous creature possesses Gaius, leading the once-wise physician to develop a taste for gold, ale and magical jokes.
With a suddenly-bald King and a scourge of flatulence sweeping the royal household, can Merlin work out what is going on and banish the Goblin back to where he came from before any real damage is done?