WIN or lose, simply being nominated for an Academy Award is an accolade not many actors attain. Sophie Okonedo is one of the few. Eight years ago, the London-born actress was nominated for her supporting role in the movie Hotel Rwanda.

She may have lost out to Cate Blanchett, but Okonedo experienced the hullabaloo and career-enhancing effect of being given recognition by the Academy.

“It’s certainly really helpful in getting things off the ground, so it’s very useful as currency,’’ says softly-spoken Okonedo, 44. “As for getting you going in the morning, it doesn’t matter,’’ she says.

Her latest project is a thriller for BBC One called Mayday, in which Okonedo plays ex-police officer and housewife Fiona and looks almost unrecognisable in dreary clothes, little make-up and glasses.

“She’s a good mum and always really applies herself to everything she does, but at the point of when the story starts, she’s feeling a little bit fed up with just being seen as a mother and looking after her children all the time.

“She misses the excitement of actually working,’’ says the tall, striking actress of Nigerian and Ashkenazi descent, who is also a mum herself.

Set in an idyllic town in the Sussex Downs, the story begins with the disappearance of local girl, Hattie, on her way to the May Day parade.

“Fiona sees it as an opportunity to dust off her old police badge and start investigating to try and find out what might have happened to her,’’ explains Okonedo.

But unlike other murder mysteries, Mayday writers Ben Court and Caroline Ip (of Whitechapel fame) have created a drama that’s far removed from the familiar incident rooms and crime scenes.

Over five consecutive nights the drama follows the mass hysteria and ensuing search from the point of view of the central characters.

It’s a true ensemble piece including the likes of Bafta-nominated Lesley Manville and Oscar-nominated Peter McDonald.

“I had an amazing time working with Peter,’’ says Okonedo of her on-screen husband. “He's such an intelligent actor and it was just fun to work out how we do things on the set really. He’s also really funny so that just made it for me.’’

The writers were inspired after watching an episode of Crimewatch in which the public were asked to contact the studio if they knew of anyone in a certain area they believed capable of a particularly heinous crime that had taken place.

During the update, it was revealed three people had called in, each naming a possible suspect. The writers found that fascinating.

And so Mayday began with the thought: What would it feel like to suspect someone you love of a terrible crime?

“It’s not a normal murder mystery,’’ says Okonedo. “There are lots of twists and turns. The characters seem really normal but then you scratch the surface and they’re all strange and just off centre.’’

Given that the cast were not allowed to see the final script, none of the actors knew how it would conclude.

“You’re shooting scenes without knowing how it’s going to end but you just have to trust your director,’’ says Okonedo.

Instead they shot scenes with a variety of intentions “so you've got a lot of outcomes and possibilities’’.

She adds: “In one take you might act like you know something, in another you don’t; in one you think someone’s innocent, in another they’re guilty.

“I’ve done so many different takes, I don’t know what I’m doing,’’ she laughs.

The RADA-trained actress, who made her small screen debut in 1991’s Young Soul Rebels and has gone on to be Golden Globe-nominated for Tsunami: The Aftermath and Bafta-nominated for Criminal Justice and Mrs Mandela, says she rarely watches her performances.

But she might make an exception for Mayday. “I don’t know what kind of character I’ve ended up playing,’’ she says.

“Fiona’s essentially the same person but she’s got a different objective in each take, so I think I’ll have to watch it to see how it pieces together.’’

Shortly before shooting Mayday, Okonedo wrapped on After Earth, a mega-bucks sci-fi movie in which she plays the wife of Will Smith and mother to his real-life son Jaden.

“I do have really good luck in that I get to do things like that one minute, then this and play readings at The Royal Court Theatre the next,’’ says Okonedo.

At the moment she’s keen to get back to the stage.

“I go by the experience of whether I want to work with someone. Will the experience be interesting and creative?

Mayday begins at 9pm on BBC One on Sunday and runs over five nights