Silent Witness (BBC1, 9pm)

THE number 13 is unlucky for some, but if you are part of crime drama Silent Witness it couldn’t be luckier.

For the crack team of forensic pathologists, Professor Leo Dalton, Dr Nikki Alexander and Dr Harry Cunningham, are back for the 13th series and facing their toughest challenges yet.

“It’s been a darker series, with a lot to get our teeth into,” says Tom Ward, who plays Harry.

The drama doesn’t even take its time to warm up. Leo ends up in a coma during the first two-parter, after he is accused of meddling with a post-mortem examination – of which he has no recollection.

“I have to go on a life-support machine and very nearly die but, I’m happy to say, not quite,” says William Gaminara, who plays Leo.

“It’s such a good episode because it’s about recovering from that and whether he goes back to work too soon. He takes on a big case and he’s struggling to keep up with it. It very much colours the episodes after that too.”

The coma scenes were hard on the actors, not least for Emilia Fox, who plays Nikki. “We’ve been working together for so long, the three of us, and I know his character so intimately, the very thought of not having Leo around was genuinely upsetting,” she says.

The situation is further complicated by the fact that Leo, who lost his wife and daughter in a car accident, has written a will which puts the responsibility of deciding whether to leave him on the lifesupport machine to Nikki and Harry.

This series also sees Nikki and Harry facing a professional crisis when they disagree on a case. That’s something that’s not been seen before, says Ward.

“It’s a murder case, obviously, about a woman who’s found dead at the bottom of a staircase and the big question is, did she fall or was she pushed by her husband, who’s a very successful writer?,” he says. “I think she was pushed and Nikki is on the side of those who think it was an accident.”

Fox found these scenes tough too as her character learns of a different side to Harry. “I found them upsetting,” she says.

“There was one scene where he shouted at me and I burst into tears in rehearsal.

It really scared me – he was horrible.

I burst into tears because he was so cross with me and I hate having rows.’’

THE actors have met real pathologists as part of their research and watched post-mortem examinations.

“It is grisly, removing everything is grisly but when they take it all away and it gets to the dissecting, it becomes very minute,” says Ward.

Fox adds: “It makes you understand more about the body because you see how it all works and that stops you from feeling squeamish because you become so riveted by, ‘oh no it’s not the kidney that killed them, it’s something else’.”

Surely working in the milieu of death and bodies must make them more health conscious?

“It makes you think about it because we’ve seen the insides of someone’s body, we’ve seen hearts, brains, livers and what they should look like when they’re healthy and when they’re not, so it’s food for thought, yes,” says Fox.

The new series sees the action take place in some rather unsavoury locations.

“We’ve filmed in some horrible places, like that car park when everyone was avoiding stepping in poo,” says Fox.

“I had three days on my knees in a dirty urinal,” adds Ward. “I had to be practically in the same position with the urinal flushing every 20 minutes.

“In the scene there’s a guy that’s been shot and I’m looking after him. It’s good stuff because we think he may be the killer and I have to extract bits of bone from his head. I was very happy to finish that scene.”

■ The series continues tomorrow at 9pm.