Bradley Walsh returns as DS Ronnie Brooks in an arresting new series of Law & Order UK.

Will we see more of Ronnie’s personal life in the fourth series?
“There are glimpses. You get more insight into his opinions on things throughout the show. Ronnie’s a wonderful character, he sees both sides of every story and can understand why someone does something dark – even though he’s got to nick ’em!”

How does the new series open?
“An ex-premiership footballer gets murdered and everyone suspects a man called Mike – played by Lorcan Cranitch – of killing him because he is in the wrong place at the wrong time. It’s a really strong opening episode.”

Are all the storylines quite as dark?
“Our show isn’t as graphic as some others – we don’t have blood and gore in every scene, but most of the stories are quite harrowing. Law and Order is concerned with the psychological implications of crime and can be quite complex. We tackle social issues without being sensationalistic.”

Do you think that is part of the show’s appeal?
“Yes, I do. We’ve had great feedback. Our show is a bit of a one-stop shop – you’ve got crime, cops and a courtroom drama, and it’s all done in an hour! And, because all the episodes are stand-alone, you can dip into it whenever you want, without feeling you’ve missed anything!”

So what else can we expect this series?
“There’s a storyline involving a governmental conspiracy were someone’s been given a new identity. And there’s a harrowing story about a copycat killer that we hope will prick people’s conscience. It’s wonderful to be on a show that really tackles big issues.”

The last three series had great guest stars, who can we expect to see this time round?
“Eddie Marsan returns up as defence barrister Jason Peters in episode one. Juliet Stevenson and John McArdle play husband and wife in the second episode. Nicola Walker stars as a therapist in the third episode and Diana Quick turns up as a judge later in the series.”

Ronnie loves to eat, is that a struggle for you to film?
“That can be a major problem! We were filming a scene where I’d have to eat a slice of an 18-inch pizza while walking and talking to Harriet Walter (DI Natalie Chandler) and Jamie Bamber (DS Matt Devlin). We did 15 takes! Later I worked out that over two hours I’d eaten about 4 full-size 18-inch pizzas! I couldn’t eat for days afterwards!”

Series four of Law & Order UK stars Monday, 7 March at 9pm on ITV1.