Now knowing Merlin's secret, Morgana uses an ancient creature to steal Merlin's magical powers on the eve of her full-scale assault on the kingdom of Camelot.
Instead of waiting for his sister's army of Saxons to besiege his citadel, King Arthur decides to ride out with his army and face her in a mountainous defile known as Camlann.
Merlin however realises he cannot accompany Arthur on this possibly final journey as he must go to the "birthplace of magic", The Crystal Cave in the Valley Of Fallen Of Kings, and try to get his powers back.
I realise that this is what the show has been building to five years, and this particular episode was only half of the final story, but The Diamond Of The Day felt rather lacking.
Not only do we have the contrivance of the only survivor of a slaughter turning out to be Morgana's agent, but then when Morgana learns that powerless Merlin is going to the "birthplace of magic" to try and get his powers back her plan is to... trap him in there. In The Birthplace Of Magic. Where he wanted to go anyway. Didn't she see the flaw in her plan?
Rather strangely as well the legendary Battle of Camlann was rewritten as a clone of the Battle of Thermopylae (as depicted, most recently, in the movie 300), completed with secret path.
On the plus side there was a nice cameo from the ghost of Merlin's father, Balinor (John Lynch), who helped guide Merlin through his imprisonment in the Crystal Cave to his DESTINY (must be read in dramatic voice). Which he was only able to achieve because Morgana had trapped him in there. After going to great lengths to strip him of his magical powers.
I suppose this could be seen as the ultimate irony. But it could also have been seen as slightly daft and slightly underwhelming.
Even what we have seen so far of the battle at Camlann didn't amount to much (especially when compared to some of the big battles the show has hosted in the past), taking place at night (no doubt for budgetary reasons) and mainly consisting of groups of men running at each other.
I guess I was just expecting more.
Let's hope the final - ever - episode of Merlin, the conclusion of this two-part finale, makes up for this episode's shortcomings.