The fourth season of “Law & Order Toronto: Criminal Intent” opened with a goodbye. Det. Sgt. Henry Graff is gone, and Frankie Bateman, played by Kathleen Munroe, now works alongside a new partner, Det. Sgt. John Darcy, played by Luke Kirby.

For Munroe, the shakeup made the season feel like a fresh start.

“I think this one almost felt like a new series,” Munroe said on “The Wayne Ayers Podcast.” “I have a new costar in this. And so so much felt like we were reintroducing, and there’s a new dynamic, and there’s a new kind of energy to it.”

At the same time, she said, the show pushed further than before. “I think we did some more challenging stories this year, some more challenging cases, and grew a little bit into the characters,” she said. “And so it was kind of this strange mix of starting all over again, but then also being able to push things a little further sometimes.”

The cast had little time to prepare. “We didn’t have much lead time. We didn’t have rehearsal, really,” Munroe said. “And so it was just kind of jumping in and finding it as we go, which I think wasn’t so much hard as it was just a discovery process.”

She credited Kirby, whom she has known for years. “He’s such a good actor, and he’s such a good teammate, and so it made it more fun than difficult,” she said. “But there’s still the feeling of, no matter how it feels on the inside, are people going to respond?”

Finding each other on camera

Munroe and Kirby worked together years ago on an episode of the Canadian police drama “Flashpoint,” where they played a couple on a crime spree.

“It was a really intense episode where we played a couple where I was dying, and we were on a crime spree, and we’re really in love and upset,” she said. “And I think because it was so intense, we just developed a trust and developed a real ease with each other in some pretty intense scenarios. So the chemistry was there.”

When producers floated Kirby for the role, she didn’t need a chemistry test. “I was like, great. We don’t really need to get in the same room and see if it works,” Munroe said. “I know that we have a really easy, really good rapport and we’re very trusting.”

Nobody knew how Frankie and Darcy would get along. “We were like, OK, what is this dynamic? What is it going to be?” she said. “At first I was a little bit like, tell me more. I want to know where this is going because I want to know what to play.”

“But looking back, the sort of joy of it was, we actually didn’t know,” she said. “What you watch when you see it is two partners kind of finding each other, and that’s really what we were doing in real life.”

Darcy’s years undercover give him a different toolkit than Frankie’s profiling. “Because he was undercover so much, he can kind of blend with all kinds of different people,” Munroe said. “So when it comes to extracting confessions or information, he’s really good at just locking in with people in a way that makes them feel like he’s sort of among them.”

Frankie, though, is still sizing him up. “There’s a bit of a, who is this guy? How does he know how to do this so well?” Munroe said. “And I think the trust between the two grows over the season. I don’t think it’s immediately there.”

In the premiere, she said, Frankie pushes back on his approach: “Hey man, this isn’t how we do it in Homicide. You can’t just go in and be really hard on the victim’s family, even if you think they’re complicit in something. It just doesn’t work that way.”

“So there’s a little bit of a learning curve for both of them,” she said.

The turning point

Munroe said Frankie’s trust in Darcy had to be earned on screen. “It was something early on that I was like, we need to find that because we have to earn it,” she said. “We don’t see the scripts until right before. So it’s sort of a matter of learning as we go.”

The first real shift comes in “The Business of Boys,” an episode about the manosphere that pulls the detectives into high school gender politics. It aired third but was originally slated as the season’s fifth episode, at its midpoint.

Munroe pushed for a scene that went in and out of drafts, and writer Steve Cochran made room for it. After Darcy quotes manosphere rhetoric to a kid to get him talking, Frankie studies her partner. Back in the car, the two discuss the 1989 massacre at Montreal’s École Polytechnique; Frankie asks how he knows so much, and Darcy tells her about his nephews.

“It’s the first kind of personal thing we hear from him,” she said. “To me, it’s that. It’s that when I go, OK, I can see the human here. There’s a human here who is really doing this because … the level of investment that he has in his family, which is motivating a certain aspect of his investigation, I can vibe with.”

“By the end of the episode, I think I see him really do well to get what we need,” she said. “So I think that’s the first main moment.”

Munroe praised Kirby’s work in the episode’s final scenes, when Darcy faces a man steeped in toxic masculinity. “He did it in this really beautiful way,” she said. “I think that was an example of the character being able to, on the one hand, take control of a scenario and guide it where he wants to.”

Director Chloe Robichaud set the mood. “She was like, I think she’s not sleeping, and I also think it’s really hot out,” Munroe said. “And so we had fans on and jackets off and cold cans on because it just makes things edgier.”

The season finale, she said, takes the partnership further. “The finale of the season, I think, is one of our best,” Munroe said. “There’s some stuff that happens in that that really, I’m just going to say, solidifies the dynamic between us. It feels like it goes to a next level.”

A rough season off camera

The episode order changed partly because of Munroe’s health. She started production with a broken foot, then had a concussion, a collapsed lung, and mononucleosis.

“This is not to be like a drama queen, but just to really point out how great the people that I work with are,” she said. “It was just dumb, stupid random stuff. … So I just was not in good shape. I had to take a couple days off, which I’ve never done in my career.”

“We just needed some more time because I wasn’t there for some of it,” she said of the reshuffled episodes.

The injuries limited what she could do physically. “I couldn’t crouch and stand,” she said. “I realized how much in ‘Law & Order’ we’re crouching to look at things and stand. All these physical things. So they had to be really creative.”

Some scripts were rewritten, and Kirby carried more of the load. “Luke, as Darcy, really came into the fold in a pretty serious way to help pick up the slack and not make it so obvious that I wear a lot of sunglasses early on because I was quite concussed,” Munroe said. “You may notice more sunglasses in this season.”

“There’s a really creative team working to make sure it’s all seamless, even when things are a little bit wacky,” she said.

Darker cases

The season wastes no time. Its second episode follows a killer who mails body parts and hides behind legal loopholes.

“They go for it in this season,” Munroe said.

She told the team the episode struck her as disturbing. “I think there’s something sort of upsetting about this, even though we’re supposed to be to some extent inured by dead bodies,” she said. Near the end, she asked to explore how Frankie feels about time away from her daughter, and the writers and director agreed.

“Things are a little more intense. It’s a little darker,” Munroe said. “Things aren’t as clearly good and evil as sometimes you find in these shows.”

Frankie also plays bad cop more this season, Munroe said, including in an episode about the murder, decades ago, of a Canadian soldier in Afghanistan. It was set to air the night of the interview.

“There’s one tonight where Frankie kind of rips into someone and then realizes that she was wrong about it,” she said. “She kind of goes really hard at somebody with some assumptions about who he is and what he was doing, and then realizes that, oh, actually, that’s not the whole story.”

“That is part of policing, right? It’s getting it wrong,” she said. “They really kind of let me go hard at him. And I think it’s fun to do because you get to see the fall afterward of, oh, I got it wrong as a cop right there. And I think that just adds some realness and honesty to the dynamic.”

Without giving away the ending, Munroe said the case turns on suspicion. “There’s an assumption of terrorism,” she said. “It may be true. It may not be true. We’ll see.” The episode, she said, “deals with broader assumptions about people and who’s telling the real story.”

Still to come is an episode about artificial intelligence, written by Sam Godfrey and featuring guest star Maev Beaty, whom Munroe called “an incredible actress.” Munroe noted how quickly AI has changed since it was filmed.

“It’s actually quite a devastating episode,” she said. “It deals with what we hope AI can do as well as what some problems might be. So it’s not like ‘Mission: Impossible Dead Reckoning,’ something infiltrating all the systems and it’s all bad.”

“It’s more like, what would we as humans hope we could use this technology for in a way that’s really relatable and really kind of speaks to the heart of humanity?” she said. “And then what are the pitfalls of that, or where does that lead?”

Munroe, who called herself “such a Luddite,” said she is only now replacing an old phone because it is breaking. “I’m not great with technology,” she said. “I can understand, though, why some people would want to use these technologies in certain ways over others. And I think the question of what can we gain and what do we lose from this is really interesting.”

Another upcoming case involves possible arson, and Munroe said it rattled her character. “Frankie does not like burn victims. It’s horrifying,” she said. “This was a young woman, so … that was one where I was like, she hasn’t slept.”

Cronenberg, motherhood and a pinky ring

The second episode also introduces Frankie’s father, Dr. Levi Bateman, played by filmmaker David Cronenberg, a casting choice Munroe said: “blew my mind.”

After talking with the writers, they rewrote a scene between father and daughter. “I think Frankie really wants to be at these family dinners, and I think her parents see her kid more than she does sometimes,” Munroe said. “And I think that’s maybe a little current underneath things.”

When her father asks to come over for dinner and says they’re making the favorite meal of Frankie’s daughter, Rowan, Frankie’s answer carries that tension. “The feeling of just being like, you know I want to be there, and you know I can’t promise,” Munroe said. “And I think that reality is so true for so many people.”

“It’s not a matter of wanting to be there for your kid or with your kid or not,” she said. “It’s just a matter of how to balance all this stuff. And it’s not easy.”

Munroe said she keeps Frankie’s life as a single mother present even when the script doesn’t mention it. “It’s something that I try to play even when we don’t talk about it on screen, because I think it lives in people,” she said.

“For Frankie, I think she has to really believe that this system, that the criminal justice system is the way to keep her daughter safe in the world,” Munroe said. “I think she just really thinks this is a devotional thing because otherwise she would be home with her. And it’s a job that doesn’t keep regular hours. Often goes through the nights, through the weekends.”

She also relies on a small prop. “I always wear a pinky ring with Frankie’s daughter’s initial on it,” Munroe said. “And so I’ll just kind of touch and be like, right, she’s at home, so I want to go fast because I want to get home to her.”

What she would tell Frankie

Munroe described Frankie as a character shaped together with series creator Tassie Cameron, who she said: “put a lot of herself into it.”

Asked what she would say to Frankie if she could, Munroe said the detective can be dogged. “I think it’s really when the system doesn’t work in a way that she wishes it would, it gives a bit of a crisis of faith,” she said.

“If I met Frankie in the real world, I just would want to tell her, it’s OK. You’re doing your best,” she said. “I think I would tell her to have a little fun. I’d tell her to go out once or twice and have a little more fun.”

“I do think she comes from a really honest place,” Munroe added.

Some cases stay with Frankie. Munroe pointed to the finale of the first season, which involved a young agent with the Canadian Security Intelligence Service who had been assaulted, and to a first season episode inspired by a radio host.

“Wishing she could do more for that girl, wishing she could do more for some of the women who find themselves in scenarios where they do extreme things, like perhaps murder, because they’ve been victimized,” Munroe said. “I think she doesn’t sleep sometimes when she feels like justice hasn’t really been served.”

She brings that exhaustion to the set. “Sometimes I just like to play the scenes, even if no one notices, … I’m in the office just feeling like I have not slept,” she said. It makes everything “a little bit sharper, a little edgier.”

Munroe said she sometimes acts as Frankie’s advocate. “If I see something that doesn’t really connect from the inside, there’s always room to have a conversation with the writers about that, and they’re really responsive,” she said.

Frankie has taught her something, too. “There’s something comforting about believing in good and evil, about believing in right and wrong,” Munroe said. “I don’t operate like that in my life. I don’t think that’s the way the world works.”

“She can be quite heady, and she can be quite analytical, but she’s also quite heartforward,” she said. “I do, as a human and as an actor and as an artist, like to live in the space of ambiguity. And I think what I’ve learned from Frankie is sometimes it’s OK to just go, this is bad, or this is good, and then know that the nuances are there.”

Crossover dreams

Asked which franchise detective would best complement Frankie, whether Olivia Benson, Elliot Stabler or Robert Goren, Munroe chose Benson. “Mariska is the GOAT,” she said of Mariska Hargitay.

Years ago, Munroe guest-starred on “Law & Order: Special Victims Unit” as an abuse survivor on trial for castrating a man. Hargitay held her in the courtroom as the verdict was read. “She’s crying. I’m crying,” Munroe said. “And I was like, this is interesting for a cop, right?”

“It’s a lot of, no, it’s protocol. We don’t show the human,” she said. “But she does, and sometimes we do. So I think Frankie would want to go and learn from her how to work at that high level while also still maintaining the humanity.”

“How do you maintain your humanity while also doing this thing that requires humanity to do it well, but also requires the sort of suppression of some of that to be professional?” she said.

For contrast, she named Jerry Orbach, who played Det. Lennie Briscoe on the original “Law & Order.” “I’ve begged to eat on the show because I love the way he used to eat walking around,” Munroe said. “This is actually a guy who’s just cool as hell and can just, without getting too emotional, without having his sort of equilibrium disturbed, have a little bit of pleasure in the job.”

For a Frankie and Benson crossover, Munroe would pick a trafficking case, noting that the original “Criminal Intent” premiere had a link to Montreal. “I think trafficking because it would really justify the collab, and it would sort of expand outward from both of the jurisdictions,” she said. “And then learning about what the differences are in the criminal justice system too is pretty fun.”

Her dream guest star is Jill Hennessy, the Canadian actor who played prosecutor Claire Kincaid on the original “Law & Order.” Munroe watched the show growing up. “This one’s Canadian. Jill Hennessy’s Canadian,” she said. “And so I was like, how does she get to do this?”

She would cast Hennessy as “a relative or a psycho murderer. I don’t know. Something really cool,” calling it a “full circle” moment.

And if Frankie were framed for murder and had to clear her name? “See, now I want to write that episode,” Munroe said. “She would go north.” Muskoka, where Frankie has family ties, would be too obvious, so she might head toward Tobermory or Manitoulin Island and lie low. Munroe added that she and Kirby share a running joke that if either of them ever escapes, they are headed to Rochester.

“I think she would try to secretly contact either Darcy or Holness and just go human to human about it and be like, you know me. This is not me. You got to help me out here,” she said.

Toronto plays itself

Munroe has one Toronto story she would love to see on the show: the IKEA monkey, the 2012 case of a small monkey in a shearling coat found wandering outside a Toronto IKEA.

“I think we got to have an IKEA Monkey episode,” she said. “What a unique thing that is and was, and the questions it brings up too, I think, are pretty interesting.”

The writers take inspiration from headlines but invent the murders. “To my knowledge, it’s all Toronto. It’s definitely all Canada,” Munroe said. “It’s always grounded in the city … whether it’s a cultural community, a neighborhood, a location, a school, whatever.”

“What are the circumstances that would drive somebody to kill somebody else?” she said. “I think that changes place to place to place to place in some ways.”

She pointed to episodes about diploma mills that prey on students who come to Canada and about bread price fixing. “The murder is invented, but the idea that big corporations are price fixing groceries is, that’s a reality, and it sucks,” she said.

Weather is part of it, too. When the show first shot in February, Munroe said, there was pushback on the detectives wearing parkas. “We really had to explain, if you want to do a show about Toronto, there is no way these people are out there in thin wool coats, no matter how nice they look,” she said. “That’s not my city.”

“Are they cute? Who cares?” she said of the parkas. “Did I wear a toque a couple of times and they said, ‘ Please don’t ever wear that toque again?’ OK. But you know what? It’s real.”

In one scene with Aden Young, who played Graff, the wind made both actors tear up. “A tear came down and then froze to my cheek. And he was like, this is crazy,” Munroe said. “That’s our city.”

The very first episode went to Filmore’s Hotel, the storied East End strip club hotel that no longer exists. “I was like, oh, we’re doing Toronto,” Munroe said. “That is off the beaten path enough, but if you know, you know.”

The show has also filmed at Grossman’s Tavern and in Scarborough and Etobicoke. It shot at Cafe Diplomatico in Little Italy, two doors from where Munroe’s brother used to live. “That’s been around forever, and I still love it,” she said. At the popular pizza spot Badiali, she had one complaint: “There should have been a line outside.”

“I also get to see a lot more of the city than I normally do because I’m such a creature of habit,” she said.

Fans approach her often. “The people are so nice,” Munroe said. “It’s just a show that people watch. … I’ve recently had a bunch of people being like, oh my God, my mom loves your show, or my grandma watches your show.”

Once, a worker moving streetcar track called out, “Hey, Law & Order.” “It warms my heart. I love it so much,” she said.

She is a fan of the city’s food scene, too. “The food in Toronto is so good,” she said, pointing to its Caribbean, West Indian and Jamaican spots.

Behind the camera

The material is dark, but the set is not. “Karen Robinson laughs. If she laughs one time, everybody will laugh,” Munroe said of the actor who plays Holness. “She’s infectious. And she’s so funny, and she’s so vibrant.”

Kirby, she said, is “one of the sneaky funniest people I’ve ever worked with.” “He and I will kind of just quietly get each other going,” she said. “We’ve definitely kept each other sane during some of that dark stuff, for sure.”

The crew has been largely the same for four years. “It really feels like family. We really have each other’s back,” Munroe said. “You’re with people for long enough that the kind of walls break down, and you can just be idiots around each other.”

The cast settles down when guest stars carry the heaviest scenes. “When guest stars come in, and they have to do the emotional heavy lifting, they’re going through grief and trauma, … we rein it in. We try to make a good little house for them,” she said.

She said the actor who plays pathologist Lucy DeSilva may be the most different from her character. “Her character is really kind of rigid, straitlaced, intelligent,” Munroe said. “And Nicola is the most vibrant, sunny, hilarious person. … The vibe on set is very different than the vibe that ends up on camera a lot of the time.”

Munroe hopes to direct. This season she shadowed director David Wellington on the first episode, sitting in on prep and production meetings. “I would love to. I mean, I hope to,” she said. “I’m doing everything I can because it’s another layer of storytelling.”

Writing is another matter. “The writing of this show is like calculus,” she said. “It’s character and math.” The franchise follows a Dick Wolf bible that runs 80 pages, she noted.

“And then also, you have to keep it creative and fresh and new. And you have to keep people guessing, but also follow a really tight case,” Munroe said. “My hats are off to the writers that do it.”

Frankie’s legacy

Munroe sees Frankie as a classic “Law & Order” archetype, a grounding force beside more idiosyncratic partners like Darcy and Graff.

“You don’t need to sacrifice humanity for justice,” she said. “She’s meant to be a very, very good cop, so an excellent cop, intelligent, tough, all of that stuff, but there’s still something sensitive there.”

She said Frankie shows a detective can be tough and smart while still leading with her heart. “I think it can maybe be both,” Munroe said. “And I mean, she’s got some good pantsuits.”

The wardrobe seems to follow her home. Munroe praised costume designer Nicole Manick and said she brought three pairs of shoes to Los Angeles, including one worn by guest star Jenny Raven in the AI episode. “And they showed up in my trailer magically, and then I have them now,” she said.

If the show ever ends, she knows what she would keep. “I would take the ring. The little Rowan ring,” Munroe said. “It says R on it.”