Award-winning Irish actress Elaine Cassidy tells us about her starring role in the new American horror series, Harper’s Island, which screens on BBC Three on Sunday, September 6.

The show is set on a fictional island off the north-west coast of the USA. How is your character, Abby Mills, connected to the place?
“Abby is returning to the island for the first time in seven years – since her mother was slaughtered there by serial killer John Wakefield. Abby found her mum hanging from a tree, which isn’t very nice and has haunted her ever since. She’s going back to support her best friend Henry who is getting married, but she’s making a lot of sacrifices in order to be there for him. She hasn’t been in contact with a lot of people, including her dad.”

Apparently Abby’s been reassured that the island has moved on since the tragedy, but it’s not long before the killing starts again…
“You’re guaranteed at least one death an episode! It’s not highbrow stuff, it’s popcorn entertainment. But it’s great fun and you’re going to be on the edge of your seat. Week by week characters start to get bumped off, you never know who’s next. The audience might find themselves rooting for certain people to cark it, or other people to make it. They might be rooting for the killer.”

Is it true that the actors didn’t know who was going to be bumped off next?
“Yes, we were all signed up not knowing if and when we would die. Some of us had a certain number of episodes guaranteed but you still didn’t know if you’d be alive for all of them. It was like going to work not knowing if you were about to be made unemployed. Even if you did die you couldn’t tell people you were off the show, because then people could work out whereabouts you died in the series. It was all very cloak and dagger – a web of lies. Even my family don’t know what happens!”

Apparently we don’t have to wait long for the gore to start – the first murder happens just 10 minutes into episode one when someone comes a cropper in the propeller blades underneath a boat…
“Yeah, that’s particularly nasty! One of my favourites is when a character ends up chopped in half – that’s nice isn’t it? The writers are very creative with their murders. It’s not for the faint-hearted but it’s comedy gore. I think fans of slasher films will be impressed to sees stuff like this on TV. It’ll make you laugh as much as anything – don’t take it too seriously.”

Is it right that the show is actually filmed in Canada – even though it’s supposed to be set off the coast of Seattle?
“Yes, in and around Vancouver. It was a hard shoot pretty much all on location, which made it quite intense. The weather was so changeable. By the end it was winter and snowing, but the series is set over a week in autumn. So that was a test.”

You appeared in the 2001 movie The Others with Nicole Kidman, but you’re also known for TV roles such as Maud Lilly in Fingersmith and Lucy Honeychurch in A Room With A View. What differences do you notice filming a North American drama?
“The budget is bigger and you get your little perks. There’s a table load of sweets and things on it, which you don’t get here. But the hours are longer. There are pros and cons to both.”

Is it true that Harper’s Island ends after just one series?
“Yes, which is quite unusual for a US show. At the beginning they didn’t know what they were going to do with it – they obviously want their shows to run and run so they make money. But this can’t really run for years because everybody is going to be dead by the end! It’s a self-contained 13-episode story.”

You’re married to actor Stephen Lord, who you met on the set of The Truth in 2006. Where are you guys based?
“I just go wherever I’m needed. Recently I’ve been splitting my life between London, LA, Dublin and Manchester – wherever work takes me. I’m pregnant right now, I look like a beached whale, so casting directors aren’t interested. I have to wait until this production has been manufactured! I’m raring to go again though.”

Interview with Andy Baker