When the former star of the police crime show enters town, local real-life detectives can hardly believe her luck.

So the plot of the BBC's new comedy crime drama Death Death Valley was shot entirely in Wales, where Timothy Spall and Gwyneth Keyworth paired out to portray an unlikely crime-solving duo.

In recent years, Wales has become a popular destination for film and television production, but often stands elsewhere.

However, the action of Death Valley is firmly located in Wales - despite being in a fictional town - and contains the country's culture and landscape.

"It's great to hear Wales talking... It's also a celebration in Wales," Spall said.

Spall portrays Det Sgt Janie Mallowen's favorite TV character John Chapel, played by Keyworth.

Det Mallowen worships the church after the TV show Caesar helped her through one of the darkest periods of her life.

But she began to discover that the man's church was not exactly the same as the actor's church.

The show's writer Paul Doolan admitted to being "a murder obsession".

“I like the idea of ​​a TV actor who plays the detective and their fans and the awkward relationship, but I really can’t get beyond the other fun about it.

"Then I thought 'What if they resolve the murder?'

On the show, Spall's character first meets Det Sgt Mallowen when his neighbor was murdered and she arrives to investigate.

"All relationships, you need conflict, you need bets, and you need motivational dynamics," Doolan said.

“Get him famous and become a fan, you just need to know that and get all that dynamic right away.

"The physical difference, the generational difference, he's English, she's Welsh - only a lot of opposites piled up to make them get along with each other."

Apart from the roles in the BBC drama in the 1980s, today is the "Rural Police Sergeant who has to do all the work", Mr Turner, Mr Harry Potter, Harry Potter and Af Widshunter's iconic Barry star, never encountered "whodunnit" in "whodunnit" and admitted to never watching a lot in that vein.

“But when they’re great, people love them,” Spall said in Cardiff.

“I love it all.

"Paul was cautious in sorting everything out. So if you don't like comedy, or you don't know it, there's (crime), and if you like comedy and don't encounter crime, you do that too."

He smiled and said that the actor who was an actor gave Spall: "There was a chance to illustrate this pretentious side, and if I brought Mick out of anyone, it was myself," he laughed.

He was full of praise for his co-star Keyworth, incompetence and hidden reputation, and when she starred in West End, he first encountered killing a mocking bird with Spall's son Rafe.

"I think, bloody hell, she's fine. A few years later, we're in this weird double action."

He said her character Det Sgt Mallowen was "very practical", adding: "She is procedural, she is a policeman and has to go through all kinds of things.

"They are very candid about each other's rudeness and offensiveness, but they are always dependent on each other in some way. They will never admit that they love each other."

Behind the humor, the performance has a darker side.

Det Sgt Mallowen lost her best friend and committed suicide at 18 years old, and the drama depicts how she dealt with the trauma.

Keyworth from Aberystwyth believes that like her character, there are many people who can be associated with using Escapist TV to deal with tough times.

“It’s like her hero is back home, but then the reality that she has to deal with (the church) isn’t actually Caesar, it may actually be a bit annoying.

“For a long time, they both have been lonely and have met to some extent.

“What followed was a lot of comedy because they had a very different way of living.”

Supporting actors include Gavin and Stacey's Steffan Rhodri, Peter Kay's car-sharing Sian Gibson, Silo's Alexandria Riley and Pembrokeshire murders, and other writings by comedian and actor Sian Harries.

"Every year we have these great Welsh actors coming out," Spall said.

"It's great to hear the Welsh language being spoken. It's great to have the whole light, that wonderful sound. It's also a celebration in Wales."

Both Spall and Keyworth are interested in the wonders of the Welsh countryside, and Spall points to the convenience and speed of moving from BBC studios and city locations such as Cardiff’s Insole Court to more rural areas, such as Bannau Brycheiniog National Park.

"We saw a lot of beautiful Welsh (on the show)," Keworth said.

"There is a plot with the walking group where we can see some real, picturesque locations that just let you go, Wales is so beautiful. There is a particularly amazing waterfall."

Penarth, a seaside town in the Glamorgan Valley, also yelled.

Keworth smiled and said, "I love a dock, I am from Abstwyth myself."

Death Valley in BBC One and BBC iPlayer Starting on Sunday, May 25th at 20:15 BST.