In your own words, what's the Murdoch Mysteries all about?

Well, it's a detective series that's set in 1890s Toronto and tries to imagine how early forensic science was used to catch murderers. The main character, William Murdoch, is an intelligent, handsome and driven detective who realises that scientific techniques - such as the use of fingerprinting and trace evidence - are the way of the future.

Of course, most of his colleagues don't quite get it and regard him as a sort of brainy maverick. Luckily, he's got a pair of true believers on his side: the pathologist Dr Julia Ogden, and the naïve but eager young cop George Crabtree. These three musketeers of the Victorian era must work together and embrace the future despite the prejudice of their colleagues.

The Murdoch novels were originally adapted in 2004 as TV movies with a completely different cast. Why didn't you keep the same people for this new series?

The movies were successful enough for the network to commission a full TV series. Which sounds easy enough at first, but the logistics are tough for the actors. For example, Peter Outerbridge, the original Detective Murdoch, was able to take time out of his busy schedule to make the occasional TV movie, but couldn't commit to a full series as he was tied up with another show called ReGenesis. Likewise, Keeley Hawes and Colm Meaney, who were the other stars of the movies, couldn't tag along for the series version.

But this wasn't as big a snag as it sounds. Changing the cast actually made logical sense, as we wanted to start from scratch and create a totally new adaptation of the Murdoch novels, with a new vision.

How did you go about finding a new Murdoch? Did you audition a lot of actors before deciding on Yannick Bisson?

Yes, we ploughed through a veritable army of handsome character actors. But I had some definite ideas about the role. I wanted someone with a lightness of touch, a playful, friendly air about him, as well as a sort of vulnerability. After all, Murdoch's a fish out of water among the other police officers - he's the polar opposite of a gung-ho tough guy.

We actually conceived the whole show as warm and playful - not a grim, Charles Dickens sort of take on the 19th Century, but a flamboyant celebration of an exciting age in human history. Yannick Bisson was the ideal Murdoch for us as he exudes the kind of idealism and passion that we imagine a Victorian man of science would have.

Where is the show filmed?

Rather happily, given that the show is actually set there, we filmed in and around Toronto. Some sets were used - we actually built the police station and morgue from scratch - but we tried to do as much location work as possible, because it just lends a grander feel to any show.

Of course, the main challenge for an historical series is stopping the 21st Century from creeping in when you least expect it. You've got to be very careful you don't shoot a scene and then later notice a power line or plane in the shot. There was a lot of dressing up involved, and we don't just mean with the actors. We had to create false facades for actual streets, cunningly concealing any signs that we weren't actually in the 19th Century.

Did other crime shows, such as CSI, influence the Murdoch Mysteries?

A lot of people have called us a "19th Century CSI" because of the forensics connection. And others may compare Murdoch Mysteries to things like Poirot, or the Jeremy Brett Sherlock Holmes series of the 80s.

Personally, I've been influenced by more peculiar, genre-bending stuff like the old TV series Wild Wild West, which infused the cowboy genre with sci-fi. We don't go to such extremes in Murdoch Mysteries, but we have tried to get away from the stuffy, almost clichéd "Victorian-ness" of your average period series. In fact, I had to keep reminding the actors to loosen up and talk in a more casual, contemporary way. The trouble is, when actors put on their 19th Century garb they just automatically become weird walking stereotypes of the period! You actually have to keep telling them not to be so stiff upper-lipped. "Keep it modern" was my motto, and hopefully viewers will appreciate that.