Anna Friel was "scared" she wouldn't be able to do her 'Marcella' role justice the day after accepting the part.

Anna Friel

Anna Friel

The 39-year-old actress makes her debut as Det Sgt Marcella Summers in the crime series tonight (04.04.16), but the brunette beauty feared she wouldn't be able to portray the character - who re-launches her career in the Metropolitan Police's Murder Squad - because she "knows nothing" about "that world".

She said: "I was quite scared at one point. I said yes the next day because otherwise they'd have had to move on, or in the next few days.

"And then I started to go, 'What can I do? I can't play that, I know nothing about that world.' "

But Anna - who shot to fame as Brookside's Beth Jordache, the character who shared a smooch with Nicola Stephenson's Margaret Clemence in what was the first pre-watershed lesbian kiss on British television - soon got to grips with her "odd" alter-ego.

Speaking to 'Lorraine', she added: "Then suddenly she started to come together. We've created a new word, we go, 'Let's Marcella it up.' She's quite odd."

Former 'Coronation Street' star Ian Puleston-Davies - who played Owen Armstrong in the soap for five years - also stars in the new drama, as one of several suspects in a serial killer investigation, and feels fortunate to have been offered the role.

When asked how he feels to be starring in the upcoming show - which also stars Downton Abbey's Laura Carmichael - he said: "Very lucky. You're working alongside some of the best actors in the industry.

"I've been a huge fan of Anna for many, many years."