Ludwig: A body falls from the fourth storey of a construction site. Was it just a terrible accident, or a perfectly executed murder?

The 47-year-old Line of Duty and Motherland star plays Lucy Betts-Taylor, the wife of missing detective James Taylor and sister-in-law of his twin brother John.

Granted, she isn’t the star of the show, but her understated turn brings gravitas to a tale which could have easily crossed the fine line between escapist and ridiculous.

Although Ludwig is first and foremost a crime-solving show, Maxwell Martin believes the dynamic between the two main characters is key to its success.

“I think the heart of the show is Lucy and John’s relationship, with sleuthing as an accidental bonus,” she explains.

“Lucy and John are light and shade. Their relationship is very sweet and nuanced, written really well by Mark Brotherhood.

“Lucy is completely understanding and accepting of John, their care for each other is unconditional.

“What I like about Lucy is that she is indomitable. She is always positive, like a puppy, despite what has happened to her. John is the Eeyore of the piece.

“There is a lot of heart in this show and David and I have a good relationship in it, so I am willing it on.”

We’re now past the halfway point in the series and in tonight’s episode, Lucy’s frustration at the police’s lack of progress in finding her husband reaches boiling point.

After all, despite the other mysteries that have cropped up over the past few weeks, the search for James is still the driving force behind the show.

And speaking of other puzzles, when a body falls from the fourth storey of a construction site tonight, John has to decide it just a terrible accident or a perfectly executed murder?

The team think John (posing as James) is losing his touch when he latches on to a far-fetched theory and starts pointing fingers.

Things don’t quite add up, and the puzzle expert starts to question his abilities, both at work and at home.

Although a second series of Ludwig has not been greenlit just yet, there is plenty of scope for additional stories.

“It’s certainly our hope that it will carry on, so fingers crossed,” Mitchell says.

Exactly which direction that takes may hinge on whether John can crack the answer to the cipher left by James, which he has up on his wall.

But even if he can, that doesn’t mean it’s the end of that particular mystery.

“Even over the whole first series, that’s not all solved, which is why we hope for more,” the actor adds.

Anna also appears positive there will be another run at some point, one which her character gets the opportunity to do more detective work.

“I would get her out of the house and doing more sleuthing,” she says.

“This season we’re telling the story of Lucy being a bit green around the gills.

“If there was a series two I would get her out and into a bit of danger. I think she can do the danger more than John.”