Few actresses are as closely aligned with their screen characters as Caroline Proust, the star of the long-running French crime drama Spiral. Even when she popped up as a guest star on the BBC whodunnit hit Death in Paradise six years ago I couldn’t erase the image of Captain Laure Berthaud, the Parisian cop Proust has been playing on television for the past 15 years.

Laure is not glamorous, she’s not sociable, she certainly doesn’t follow the rules and she’s not even virtuous. She looks scruffy and bedraggled and God forbid that she should crack a joke. Yet such is the power and off-kilter charisma of Proust’s performance that we love her dogged crime fighter nonetheless.

Proust loves Laure too. After all, the show — called Engrenages in French — has catapulted her to international attention and given her the role of a lifetime. But as series eight begins on BBC Four, Proust isn’t mourning the fact that this will be the final installment. “It’s time to do something else,” she says. “To play the same character aging from 35 to 50 is definitely a very nice present for an actress but I’m happy to let her go.”

In its early days Spiral was more of an ensemble piece, a sprawling examination of the French judicial system, from police to prosecutors, from judges to the criminals and their lawyers. But as it has progressed, Proust’s character, a conflicted woman struggling with demons — including ambivalence about her infant child — has increasingly become the center of attention. And although it predates The Killing and The Bridge — those two other giants of European crime fiction — Spiral mines the same kind of feminist heroics.

“The public fell in love with Laure and needed to see her,” the 53-year-old French actress says to me on the phone from her home in Paris. Proust’s English is fluent, although heavily accented, and happily she’s a lot more voluble than Laure. Then again, that isn’t hard. “Laure is a normal person, she’s not a movie star. She’s a worker and she has problems that people don’t often discuss. The mother’s rejection of her child, the way a woman, when she wants to sleep with a man, sleeps with him and that’s that — finished. Laure is very independent and does what she wants. That kind of woman wasn’t so obvious on our TV screens before the show started in 2005. It was really the beginning of something.”

Laure is not glamorous, she’s not sociable, she certainly doesn’t follow the rules and she’s not even virtuous.

It was certainly the beginning of our love affair with Spiral and its remarkable women. Representing the other side of the law — and acting as a counter to Laure’s subdued femininity — is the elegant and flamboyantly sexy defense lawyer Joséphine Karlsson, played by Audrey Fleurot. They have evolved into the two most compelling creations in a show packed with fascinating, flawed characters. “When we began the series it was a different world for women,” Proust says. “There are now more actresses, more feminine characters in the series, just as there are more women in the police force.”

The cast of Spiral.

How does the show play with the real-life detectives who solve crimes in Paris? Proust has met enough of them to know. “They are very fond of the series because it’s realistic,” she says. “In fact some cops don’t want to see it because it reminds them too much of what they are living all day long. But others are very proud and glad that we are talking about the way they work. Prisoners are very fond of the series as well.”

Proust was as surprised as anyone with the show’s success across the Channel. “We had no idea it would be a hit in Britain. When BBC Four bought the first season it was the first time that a French series had been sold to the BBC since the Sixties. So we were very happy and proud. That it became a hit was absolutely unexpected and I’m still wondering why it worked so well.”

Spiral has done well around the world. It has been sold to broadcasters in more than 70 countries and it won the 2015 International Emmy award for best series. It’s set in the French capital, but it’s very much a Paris tourists never see. No Eiffel Tower, no Louvre, no Notre Dame cathedral. This is the bleak and gritty underbelly of a big city in which poverty and marginalization define people’s lives.

“They choose to show the Paris people don’t really know,” Proust says. “Yes, it’s definitely a grim view because the producers wanted to show the dark side. Everybody knows Paris as the most beautiful city in the world but it’s not true everywhere. There is the beautiful view and there is another view, which is where the real workers, the real people live. This season we are talking about migrants, especially those from Morocco, and it’s very painful to see how these people live and how the police treat them.

“Some cops don’t want to see it because it reminds them too much of what they are living all day long.... Prisoners are very fond of the series.”

“It’s very difficult for these young people — some as young as 12 — who are sent by their families from Morocco to Paris thinking that they will have easy money, thinking they have escaped from poverty and will be able to send money back to their families. But there are really bad people giving them drugs and then they need money to buy the drugs so they become violent. It’s a vicious circle.”

In the middle of it all stands Laure, consumed by a career “where she spends all her time dealing with society’s problems”. No wonder she eschews the trivialities of small talk and the superficialities of fashion.

“That is something I brought to the character,” Proust says. “In the first season when they asked me what kind of woman I wanted Laure to be I said that she’s very involved in her job so she doesn’t spend any time in front of the mirror. She doesn’t care about her appearance so we have to do something very natural. And police officers don’t earn much money so she can’t be very interested in clothes anyway. She just wants to wear things that can help her do her job the best way she can. If she needs to run she needs to have shoes for running, not shoes to be beautiful.”

Spiral is filmed in the eastern part of the city, which is where Proust lives. “That’s why I chose this house — it was easier to be close to the set, especially when I had to go there so many times. They were filming all around my house.” She has spent the pandemic at home with her partner (he’s a director of photography); she has 19-year-old twin daughters with her former husband, the actor Clovis Cornillac. Coronavirus brought with it an unexpected houseguest. “We also have a cat who’s a new inhabitant in our house. My daughter brought this cat home for the first lockdown and left him here. We have a garden so it’s better for him.”

Television may have made her famous but theater is where Proust will always return when the cameras switch off. It’s where she can lay Laure to rest, at least for a while. She takes inspiration from the plays of the British writer Edward Bond and the directors Peter Brook and Deborah Warner. Her credits include Shakespeare in French, and Tracy Letts’s Pulitzer prizewinning American drama August: Osage County. “Of course I want to be onstage because theater is my first love,” Proust says. “I would love to do something in Britain, where I’m told people appreciate me. Three years ago I was in Arthur Miller’s A View from the Bridge. I would have liked to come to England to show them the way we did it in the French theater.”

Like actors everywhere she is worried about the pandemic’s impact on live theater. “I hope theaters will reopen soon — it could be the death of theater if not. It’s a very difficult time for actors. We need the stage, we want to be recognized as living theater. We don’t want to be stuck behind the computer screen. There are movies for that.”

She’s not a fan of streaming theater generally and recently signed a letter to the French culture minister warning of the long-term damage that social media can present to the live arts. Streaming doesn’t benefit artists financially, she says, while the ritualized transaction between audience and actors in a theater may be lost and lead to the eventual loss of theaters themselves. And don’t get her started on the tyranny of those instant like and dislike clicks and the Internet’s obsession with the number of hits a performance gets.

For now, however, all thoughts of theaters reopening in France are off the table and Proust will have to wait a little longer to refashion her public image. Viewers in the UK, meanwhile, will be keen to find out what happens to Captain Berthaud and her complex relationship with her bulldog partner Gilou, played with a tremendous rough charm by Thierry Godard. The last we saw of him he was being hauled off to prison at the end of series seven, having exonerated her of any wrongdoing.

Will that relationship be resolved? “Yes I think so,” Proust says. “There is a very deep love between these two characters and it can’t stop. As for Thierry, it’s been a fantastic huge pleasure to spend all these years with this guy. The experience couldn’t have been the same if not for him.”

Are the eight episodes of series eight definitely the end of the line? “Oh yes, I have spent 15 years living with the character. There are always new problems for the show to highlight and I agree with that, but it has been very difficult to wear her so close. She’s depressive and she has a very difficult job as a police officer. It’s been weird to have spent so many hours, so many months with her. If I’m yelling at someone I’m yelling the same way as Laure. If I’m crying it’s the same way as Laure did. I want to do something else, I need to do something else.”

Debra Craine is a longtime writer for The Times of London, and the co-author of The Oxford Dictionary of Dance