Kim Cattrall compares Sex and the City to Witness for the Prosecution

Samantha Jones is heading to the 1920s.

Kim Cattrall plays a rich and glamorous widow who is ruthlessly murdered in The Witness for the Prosecution, a new adaptation of Agatha Christie's classic murder mystery for Acorn TV available to stream today.

Witness is a thrilling whodunnit packed with Christie's trademark twists. Set in London in 1923, the story revolves around the murder of the vibrant Emily French (Cattrall), whose body is found in a pool of blood on the floor of her posh townhouse. The obvious suspect is the young Leonard Vole (Billy Howle), who had an intimate relationship with her and to whom she recently left all her money. But as Vole's lawyer John Mayhew (Toby Jones) finds, the case is not as simple as that. Rounding out the cast of characters are Romaine (Andrea Riseborough), Leonard's significant other, and Emily's disdainful maid (Monica Dolan). Julian Jarrold (The Crown) directs, and the screenplay is by Sarah Phelps, who wrote BBC's 2015 Christie adaptation And Then There Were None.

Cattrall's character is not a far cry from her infamous Sex and the City character: She's a stylish, fun-loving feminist who goes to parties and drinks. Emily French shirks society's expectations that a widow of a certain age should be interested in boring older men. Instead, she pursues younger boys.

EW spoke to Cattrall about The Witness for the Prosecution, how the adaptation differs from Christie's original play, and, of course, those neverending Sex and the City 3 rumors.

On how this adaptation and her character differ from the original:
"Sarah [Phelps] made it her own. It was originally set post-World War II and Romaine was German [rather than Austrian] and much older than her husband Leonard Vole. I was really excited because I'm a big fan of Agatha Christie and I felt that I got to play a character that has similar traits to another character that I played [Samantha Jones], but I made her quite different, very individual, and kind of a feminist, an early feminist, and very emancipated because in the original, she's thought to be elderly. I think that changed the stakes.

"I think that it would have been easy to make her flippant and overconfident, and I saw another side, the underbelly of all of those characteristics, somebody who is in some ways in a lot of pain and overcompensating. The story that I made up for my Emily French is that she had been a young debutant and married a very wealthy man who died and she was very lonely. She had always been courted and she decided she didn't want to get married again and she was going to have this kind of life, but with that decision came a feeling ultimately as she got older and the years went by that there were fewer young men unless there was compensation. So when she asks Leonard if five pounds a day is enough, it doesn't come from a place like ‘this is the price tag I'm putting on you,' it was almost ‘this is what my life has come to — I'm having to pay for intimacy.' Yes, the sex is fun, but she really wants a companion. That's what she's looking for. So I found that underbelly was something that made real sense for me and I think that you felt more for her. She was living in the fantasy of what things used to be, which they aren't anymore, and there's only a few moments when you see her in the truth of what her reality and what her life is. That for me was a really good reason to play her: to take a given circumstance that is somewhat familiar and to turn it inside out and make it something that is quite illuminating about a woman's life in 1923."

On loving the 1957 film adaptation Witness for the Prosecution:
"I'm a big Charles Laughton fan. What I really enjoyed was Marlene Dietrich. I didn't know what she was going to do next. I kind of thought that was her when she was in the disguise but I wasn't completely sure the first time. I thought it was interesting Tyrone Power not playing a hero, playing a very unsympathetic character and a murderer was interesting. It was black and white, which I thought was really cool. Because [the Romaine character, Christine] was German, it was very close to a political statement that Agatha Christie and the filmmakers were making about post-second world war Europe and the prejudice against not just the usual suspects of the second world war but Germans who were living in England. And an American young soldier who had married an older woman. There are a lot of things in play which we look at now and don't think twice about because it's so far away."

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On being an Agatha Christie fan:
"When I was a kid [my favorite Christie book] was Ten Little Indians. I loved Clue and those games as a kid, the Poirot books I always loved. The whole world and the detail of the characters that she laid out, specifically women characters. Not just her victims but her complex heroines who weren't easy to like and you thought, ‘Are they just crazy or are they paranoid?' You never really know if they're telling the truth. You never know if anybody's telling the truth.

"There's a lot of moodiness to this production. The way it's lit and the way the story's told from the different points of view. I think that that is reflecting a lot of what is going on in the world right now, all this uncertainty and fear which was definitely happening in 1923. This material is rich enough that you can reimagine it for the time not just that it's set in but the time that we're living in. Agatha Christie is like Shakespeare. You can set her storylines in a different place and time and there's still roots there. There's still fertile ground. Because I think that the story is very strong, and the way she set it up, the construction of it, is very sound, and it can go through alterations and renovations and stripping it down or building it up."

On whether she'd want to be in any of the seven new Christie adaptations BBC commissioned:
"Yes. I don't know what they are. But yes, they're so much fun to do. Why would you say no to a whodunnit where you have a really fun part?"

On the status of Sex and the City 3 and Sarah Jessica Parker's recent comments to E! News that "there is no script" but "the idea remains a real possibility":
"I know nothing about it… I can't say this is the first time I've heard it. I think that when you hear Will & Grace is coming back, I think that's sogreat and I love that show. And that is a definite. But I don't know what's going to happen [with Sex and the City]. I feel like I'm sitting back and watching this happen. And if it does happen, that would be great; if it doesn't happen, that's good too. I think all of us on the show are off doing our own things and have been since the series went off the air in 2004. I do know something: that people right now, maybe more than ever, need to laugh. They need a diversion from the uncertainty of the times that we're living in right now which are kind of scary."

On whether she'd turn up on Sarah Jessica Parker's new HBO show, Divorce:
"Yes, of course. I'd love to be on a really good show with Sarah. I hear it's really good. And I love Molly Shannon."

Agatha Christie'sThe Witness for the Prosecution is available to stream on Acorn TV starting Jan. 30.

This interview has been condensed and edited.