Murdoch Mysteries’ showrunner Peter Mitchell says he likes to put out a scary episode every so often, and Monday’s instalment certainly fit the bill. “The Incurables” found Dr. Ogden trapped among several of the show’s most notable female criminals, including Mrs. Lynd, Rose, Eva Pearce and Charlotte, the girl with multiple personalities.

Marked with darkness, violence and revenge, the episode was noteworthy for being as much a character-driven plot as much as a murder mystery. We spoke to Mitchell about Monday’s latest episode and got him to tease next week’s “Toronto’s Girl Problem.”

“The Incurables” is a great twist on the locked room mystery. Did you come up with the idea, or was that pitched in the writers’ room?
Peter Mitchell: I wanted to do a big Julia story this year and one of my favourite characters on the show has been Charlotte, the girl with the multiple personalities. We liked the crazy old lady, Mrs. Lynd, we liked the axe murderer Rose and the Eva Pearce character … we wanted to bring all of those female characters back and make a real female-centric episode with Ogden at the centre of it. We thought it would be a lot of fun.

It reminded me of Batman visiting Arkham Asylum and being surrounded by super villains.
Yeah. It reminded me of those psychological horror movies that take place in asylums. Normally the reporter goes into the asylum and gets amnesia and has to try and get out. We wanted to do that locked room, asylum, murder mystery and try and feature Julia a little bit more. And we just hammered out a mystery. I didn’t know who the killer was until we finally got to it.

I actually thought it was going to be Mrs. Lynd.
And, without getting all preachy, we wanted to touch on how horrendous turn-of-the-century asylums were. None of them are really, truly bad guys. They’ve all been mistreated in there and the ultimate bad guys are, theoretically, the protectors. We wanted to play that card a little bit too.

What was Hélène’s reaction when she found out she’d be the focal point of the episode?
She was excited about it until she broke her arm. Then she was a little concerned about whether she’d be able to do the physicality of it. We shifted stuff around a little bit to accommodate a busted arm, but a busted arm is a busted arm and once she was far enough along in the healing process … Hélène is up for anything. She’s up to do any physical stuff that is demanded of her and it was just an unfortunate bit of timing that we had to be little bit more concerned than we usually are that she didn’t get hurt.

Much of the episode was spent in darkness in the asylum with just flashlights highlighting things. It was pretty darned spooky. Was that on location or was that a set?
There’s a studio in Toronto that we’ve occasionally filmed in. I directed a prison episode there when Julia was going to be executed. They have the bones to put together an asylum. And some of it was recreated on our stage. For the most part it was shot on location at that studio.

Anastasia Phillips was fantastic playing Charlotte and Girlie and the rest of her characters.
She’s great. Obviously Janet Laine-Green is great and Daiva Johnston is great and Hélène is great. So it was like, ‘Go to town!’

Eva Pearce is now on the loose. Will that storyline wrap up this season?
I won’t tell you. [Laughs.] She’s been a fun femme fatale to have on the show. Having her escape and having Murdoch make this choice in letting her go in order to save Ogden but then he didn’t really have to because she saved herself … she’s still in the game.

Let’s go back a couple of weeks to “All That Glitters.” Where did the idea to write about the Colbalt Silver Rush come from?
I think it came about when we found out there was a Cobalt Silver Rush. Who the hell knew they dragged more money out of Cobalt, Ont., than they did out of the Klondike? I learned that two years ago and it was hanging around in my head. We had a few incarnations of it kicking around, sort of a locked room mystery at a prospecting camp, and then we looked at an Indigenous person story that wasn’t typical … it just sort of coalesced.

I think maybe Colbalt was the main reason the Ontario Provincial Police came into being. There started to be a sort of labour dispute up there. It wasn’t really the Wild West up there, it was mining companies underpaying their workers and strikes and industrial action that I think lead to the formation of the OPP. That is a little past our period, so we didn’t really get into that.

Let’s talk a bit about next week’s episode, “Toronto’s Girl Problem.” What can you tease about that?
We learned about this girl gang in London, England, that existed during this period. They would swarm department stores and live the high life and we thought, ‘Who knows? Maybe they have a branch in Toronto.’ Dr. Grace and her friend Lillian go undercover in this girl gang. It’s another female-centred story and a big Dr. Grace story. It’s a nice, fun caper-type of episode.

Murdoch Mysteries airs Mondays at 8 p.m. on CBC.