‘Murdoch Mysteries’: Arwen Humphreys Talks 300th Episode & Hopes for Margaret’s Future

Murdoch Mysteries accomplishes a rare TV feat on Monday, April 14. Season 18 Episode 10 of the beloved detective series is the 300th episode of the show overall. The show has been running since it debuted in Canada in January 2008 with Yannick Bisson at the helm as the titular Detective William Murdoch. Also there since day one has been Arwen Humphreys, whose character, Margaret Brackenreid (affectionately called Mrs. B), became a fan favorite early on. She was so beloved that fans urged the series to make her a more consistent presence. Flash-forward to 2025, and the 300th episode is all about celebrating Mrs. B.

Murdoch Mysteries is based on Maureen Jennings’s popular Detective Murdoch novels. Set in Toronto in the early 1900s during the age of invention, Detective William Murdoch uses radical forensic techniques to solve some of the city’s most gruesome murders. Season 18 has had a bevy of notable guest stars such as Countess Luann de Lesseps, an original cast member of The Real Housewives of New York City, and Siobhan Murphy. Award-winning actor Paul Sun-Hyung Lee also joined the cast as Inspector Albert Choi, who has brought a whole new perspective to Station House #4.

Since Season 1, Margaret has usually taken care of everybody else, but the April 14 episode shows her receiving love in the form of a surprise birthday party. Her husband, Chief Constable Thomas Brackenreid (Thomas Craig), is arranging the special event in Season 18 Episode 10, available now on Acorn TV (Acorn TV is also available to AMC+ subscribers). Here, Humphreys previews the 300th episode and reflects on the show’s long history with TV Insider, in addition to sharing her hopes for the future.

Congratulations on reaching this milestone 300th episode. What was the vibe like on set when you were filming it?

Arwen Humphreys: Very playful. It was just fun. The amazing thing about having been on a show for this long is, a lot of the time it’s just fun because we’re all very relaxed. We know our characters, so we can play with the script. We’re allowed a certain amount of freedoms that maybe you don’t have when you’ve been playing a character for as long as we’ve been playing our characters. I love, love days where we’re all in scenes together because there’s so much goofing around and laughing, but everybody’s a professional and we all know how to get it together and get it done, and it’s awesome. So lighthearted, very lighthearted.

What can viewers expect from Margaret’s birthday celebrations?

Well, Brackenreid is organizing it. He does end up doing quite a good job, but there’s a lot of controversy getting her there because she thinks he’s forgotten. And so there was a really cool scene with a carriage. I got to ride in a carriage through our back lot, and it was fun. It’s one of the cool things about being part of a period show. You get to travel in a carriage through Scarborough, Ontario. We had a good time. [Viewers can expect] an excellent party, a really good time, especially for her. A very unexpected good time.

Why do you think a birthday party for her is a perfect plot for this 300th episode?

I think you need to have a celebration. Because you’ve got the Murdoch and [Dr. Julia Ogden, played by Hélène Joy] storyline, which has them in England, and I feel like you need to have the part where the viewers and the actors get to celebrate. What better way to do it than to celebrate the birthday of one of the characters? And quite frankly, given the fact that Margaret is usually the one who’s hosting things and she’s putting together the parties, I love the idea that it’s a party for her instead and that it’s Brackenreid who’s doing it, and he’s getting everybody else involved, which is also really fun because it’s all outside those characters comfort zones as well.

Stephen Scott / AcornTV

Would you call this a bit of a wish-fulfillment storyline for your character?

Yeah! Margaret wants to be seen at the end of the day, and I think that’s what drives a lot of her choices. She wants to be recognized. And I don’t mean that in that she’s self-centered, it’s not about that. It’s more about the fact that she’s a woman who has dedicated her life to running the home and the children and raising the children, but there’s a sense of self that she feels wants to be recognized. She’s not a woman who wants to fade into the background. So I think it’s actually kind of beautiful that it is a celebration for Margaret because she doesn’t get that a lot. She’s got a pretty hard husband to deal with. He’s a loudmouth [laughs].

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Are there any surprises for fans in this milestone episode?

Well, we have a special guest that Brackenreid lined up for Margaret. They were able to get a performer to come to Margaret’s party, and so that was really cool. But I think really what it is, is that we get a moment in time where everybody’s all together. And I feel like that’s the best part about it, especially in that scene. It’s everybody.

What was important to deliver in this 300th episode, both for the cast and crew and for the fans?

It’s always about inclusion. We wanted everyone to feel included in the party. One thing that is great about this cast is that everybody is as committed to bringing a good show to the fans the same way now as they were when they started on the show. So whenever we’re shooting anything, everybody is coming up with little ideas, and because of the fact that we’re allowed to run up to the director and go, “Hey, we were thinking, could we do this little interaction? That’d be really funny with those two characters.” Sometimes they say yes, and sometimes they say no. But I think it’s the joy. There’s a real joy for me working on this show.

There’s just a lot of laughter while we’re doing stuff. I mean, everybody gets down to work. I actually traveled with everyone to Kingston, Ontario to shoot the scenes with Murdoch and Ogden. I was shadowing our director. I loved being part of the caravan. I loved being with the crew from the beginning of the day to the end of the day. And I can say that even behind the scenes, our crew has the same amount of joy. Everybody gets frustrated, it’s not like we’re all dancing on rainbows and riding unicorns to work, but there’s a lot of laughing and silliness around the professionalism. Hopefully, that’s what we’re bringing to the fans so that when they’re a part of it, it’s like we’re all in it together.

Stephen Scott / AcornTV

How does it feel to be part of a series that has reached such a huge milestone?

It’s weird. This is my life’s work. I’ve spent the majority of my adult life on this show, and I’m not even entirely sure I will fully understand the impact of that until long after or ever. I don’t know. I feel like hashtags have ruined really great words because I feel very blessed and honored that I’ve been able to work with such amazing people and that over the last 18 years, they’ve put so much trust and faith in me. I mean, Margaret’s part was so small and they just started giving me a little bit more and a little bit more and a little bit more. That’s an incredible experience. I’m just really grateful and humbled and honored. It’s amazing. I actually was doing ADR a few weeks ago for one of the episodes, and I had to do some improvising as Margaret, and so I just kind of dropped into her and started improvising. And when we finished, I was like, ah, I really like playing her. She’s fun. I like her brain. It’s silly. I’m just incredibly honored.

And how nice that must feel to still be feeling that way about your character so many years into playing her. With 300 episodes down, is there anything you haven’t gotten to do with Margaret yet? What do you want to explore with her next?

In Season 18, you’re seeing glimpses of her life as a society woman. Season 17 was more her getting into the clinic with Ogden and sort of solving mysteries. I’d love to combine the two. I think Margaret’s always wanted to be a society woman, but what is it like once she gets there? Because at the end of the day, she’s a small-town gal from Grimsby, so I’d love to explore that thing where Margaret’s always been a bit of an outsider and her navigating that. And also — and I am sure a lot of women understand this, middle-aged women understand this — being an empty nester. What do you do when the kids aren’t there anymore? What do you do when your husband is maybe around a bit more often or is sort of off doing his own thing? How do you keep yourself busy? I’d love to do that. That would be really cool.

Murdoch Mysteries, Mondays, Acorn TV