Star Colin Morgan chats about Merlin’s scary new adventures as the hit BBC1 fantasy returns for series four on Saturday, October 1…

What can you tell us about the first episode?
“The series kicks off one year after the last series, with celebrations in Camelot in full swing and all the knights are there. It’s a special day on which people remember the dead and remember all those that we’ve lost. The theory is that on this special day, the veil between the real world and the spirit world is at it’s thinnest. Morgana sacrifices her sister Morgause to split the veil – and all these terrifying creatures come out, which leads to all sorts of problems.”

What can you tell us about the creatures?
“They almost appear like a small child and then they sort of turn into something like a skull! They only function at night and are really creepy. It looks like a shadow at first and then you only see it’s true form in the moment of it coming at you. I think people will be scared of this because we all have to gather around light to be safe and if you venture out of the light you’re a goner.”

We hear this series has got a lot of darker tones to it…
“It’s really cool to see the show is not afraid to go in those directions at the same time as still making it suitable for everyone. The series starts with a two-parter that seems to play on that childhood fear I think we’ve all had of being afraid of the dark and what’s in the dark and what’s lurking out there.”

“Every episode we’ve done I’ve been so excited about. In previous years you get an episode that’s a little bit light-hearted or it’s trying to break the tone and it’s trying to do something a bit lighter. There are lighter elements in these episodes, but it’s continuous in storylines. It’s feeling almost like an American season of episodes in a way. That’s what it feels like to me.”

Is Morgana as evil as ever this year?
“Yes, Morgana’s in her own sort of separate zone. She has a mole set in Camelot – Agravaine, played by Nathaniel Parker – who is Arthur’s uncle. They’re very much a good duo in terms of manipulating Arthur, making sure he takes these turns and twists that lead to certain areas. She’s really, really devious. Also, Morgana’s having visions of this old man called Emrys chasing her and she keeps dreaming about it; she doesn’t know that that’s really Merlin. She becomes obsessed with finding out who this Emrys person is and so, yes, she’s inadvertently on Merlin’s trail.”

What can you reveal about Merlin in future episodes?
“Something terrible happens in the third episode. It’s not just a blow to his self confidence, but a blow to everything. The future then looks bleak as he’s meant to ensure the future of magic and what happens, what he’s done, leads to the complete opposite.”

Merlin is shown in around 200 countries now – have you ever been spotted in a strange place?
“I was on holiday last year in Italy and went in a cable car to a really remote place, but what do you know! I was recognised. These people were obviously talking about me in Italian. And another time, I was at the top of the Empire State Building and a little kid recognised me. It’s always at the most unexpected times.”

SUBSCRIBE to TV Times magazine NOW and you could save up to 29%