The SAG- and Emmy-winning actress has always done great work, but the low-key Sundance charmer "Puzzle" gives Macdonald something new: a film that's entirely about her.

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Kelly Macdonald has an enviable list of co-stars she’s shared the screen with during her two-decade-long career. There was Ewan McGregor in her first film, “Trainspotting” (the Scottish actress was working as a barmaid when decided to hit up an open casting call for the part of Diane), then Bill Nighy in “The Girl in the Cafe,” Josh Brolin in “No Country for Old Men,” Sam Rockwell in “Choke,” Steve Buscemi in “Boardwalk Empire,” and those are just the men she’s worked alongside. On “Black Mirror,” she was memorably paired up with Faye Marsay in the episode “Hated in the Nation,” and in the Pixar adventure film “Brave,” Emma Thompson voiced her character’s mother, both a friend and a foe to Macdonald’s plucky young princess.

In just over twenty years, Macdonald has done plenty, flipping between film and television, American and British productions, and she’s often done it beside some of the industry’s other big talents. But there’s one thing that eluded her: a true star vehicle, the kind of film that puts her entirely at the center. With “Puzzle,” Macdonald gets to do just that.

Marc Turtletaub’s charming character study premiered at Sundance in January, where Sony Pictures Classics picked it up for a mid-summer release, the kind of film that just might spark to audiences looking for a breather after months of bombastic franchise films. The film, written by Oren Moverman, follows Macdonald as suburban wife and mother Agnes, who has spent most of her life taking care of her family, overlooking her own needs in the process.

The film’s opening scenes are both revealing and heartbreaking: Agnes preps her home for a birthday party, one that viewers initially assume is for her husband or one of her sons. Guests arrive, she potters around, attends to everyone, cleans up dishes, even readies the cake. Then, the reveal: Agnes isn’t the host of the party, she’s the one being celebrated, even though she had to put the entire thing together herself. While that party highlights some of the harsher truths about Agnes’ life, it does come with one silver lining, as Agnes receives a complex jigsaw puzzle as a gift. Agnes is very good at puzzles.

“The thing that’s always first is the character,” Macdonald said in a recent interview with IndieWire. “I was very interested in Agnes and I wanted to have the chance to act her story out. The fact that she is – oh, you know, this is sort of trite to say – but she is a puzzle herself. She’s very run of the mill and ordinary, but everybody’s got something about them that they don’t always get to show people around them. She’s a very courageous woman.”

As the film, based on the Argentine feature of the same name, moves forward, Agnes’ affection and skill for puzzling pushes her into unexpected new places. She busts loose of her suburban ennui, finds an alluring puzzle partner (Irrfan Khan), and readies for a puzzling competition. The stakes are relatively small, but Agnes finds her entire life changed by her new hobby, and Macdonald revels in the coming-of-age tale.

“It could have easily been about a competition and, ‘oh, are they going to win it?’ Or like, Agnes as kind of superhero puzzler, but it’s not that at all,” she said. “It’s very real, it’s more real than that.”

And while there are supporting actors there to further bolster Agnes’ story, from Khan’s mysterious Robert to David Denman as Agnes’ bewildered husband Louie, it’s Macdonald that gets nearly every minute of screen time. That wasn’t what attracted her to the film, however, though it’s certainly been a very nice byproduct.

“I didn’t think about it, to be honest. I’m a terrible one for not really thinking about things and just going on instinct and that doesn’t always work out,” she said. “I didn’t think about the lead role aspect, it wasn’t the big appeal about the film. I just wanted to play her.” Later, the actress said with a laugh, Macdonald said she “realized, a bit like Agnes, I’m a bit slow on the uptake. After the fact, I’m like, ‘oh, I haven’t played the lead for quite a long time.’ It is a bit of a change.”

Macdonald is, however, reflective when it comes to her career. After 22 years in the industry, she’s earned it. The “Trainspotting” role was weird luck, but Macdonald didn’t let it inform the rest of her career, she worked at it.

“I was so lucky when I started off in getting the role of Diane in ‘Trainspotting.’ I was never the big sort of, I don’t know, ‘film star beauty’ or anything,” she said. “I’ve been very happily getting along with my job and enjoying my craft, and learning, and playing amazing small roles and really great ensemble pieces. … After ‘Trainspotting,’ there was a lot of films trying to look like ‘Trainspotting’ and a lot of those parts did start to come up and were offered to me. Then I started, for a really long time, being offered the quiet, kind character.”

What happened next? Macdonald has a theory about that. “Then I think what happened is, I’ve been around long enough that directors and writers, they know what I’m known for and they wanted to do something different with me,” Macdonald said with a laugh. “They think that’s a really genius idea to get me play the opposite, characters with a bit more sass and a bit of an edge to them.”

Another thing that changed: Macdonald got older, and she found that the parts she was being offered – like “Puzzle,” which notably focuses on not just a woman, but a woman over 40 – were bigger, better, certainly richer.

“I’m of an age now where things are more interesting than in your twenties and thirties,” Macdonald said. “I’m a mother now and I’ve had some life experience, and all the books I read have so much about that in them. In the literary world, it’s very much geared towards a female readership and women that want to read about other women and their inner workings and thoughts. So when someone is clever enough to translate that into a film role or a TV role, it’s great.”

The actress has seen that change trickle down to the rest of the industry, too. “Puzzle” is indicative of the kind of movies that Hollywood can make, the kind of movies that Macdonald thinks it should make.

“I think there’s a huge change and it’s a good one. It’s not an anti-men sort of change or anything,” Macdonald said. “There was a lot unsaid in Hollywood and people go along with things out of habit and the way things are. The big studio bosses have forgotten there is this huge audience out there consisting of women that want to see films that aren’t necessarily about wars and fighting and superheroes and explosions and all that business. … It does seem like good business sense and it seems madness that’s not where the money is being put.”

In fact, these days, Macdonald is having to be choosier than ever with the kind of projects she can tackle. “I can’t just take off to work back to back on things,” she said, noting that when she was able to do back to back projects, she wasn’t being offered them. “I did one job a year, and sometimes it would eek up to two years and I’d start to think about a serious career change and then something amazing would turn up. … Annoyingly, now that I can’t just work back to back and go off traveling the world wherever the world takes me, I’m getting offered quite a lot. [Now] I’m turning down [roles], so I’ve definitely become a bit more picky about what takes me away from my kids.”

She does expect that things might change in the next few years, but she’s ready for that.

“I’m sure that in about 10 years, I’ll be playing old hags from then on in,” she said. “I can’t wait to! I’ve never played a witch, and I’ve got a great cackle. I feel like I’ll be working till my dying day, you know what I mean? I could play a witch forever. If I can’t remember my lines it would probably be a bit tricky, I’m bad enough in that regard at the minute to be honest. Every job I got after ‘Trainspotting,’ I felt was a bonus. Now I’m pretty certain this is it, this is my career.”

“Puzzle” hits theaters on Friday, July 27.

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