IF you love The Mentalist but have never seen Castle, then chances are this witty saga should also appeal as it exploits the same winning formula – charismatic protagonist (Nathan Fillion), gorgeous sidekick (Stana Katic), and a “will they, won’t they?” frisson that runs throughout.

You can even enjoy both in the same week as crime-buster/novelist Richard Castle and his assistant Kate Beckett return with a shocking case. A dead twenty- something woman is found hanging by her wrists from a playground climbing frame, her semi-clothed body covered in caramel sauce.

Although it has all the makings of a sex crime, “There’s no sex involved,” as Beckett points out.

Investigations take the cops to The Love Shackle, a shop selling bespoke bondage gear. The owner Barry provides handy information which identifies the victim and exshopper as Tyler Benson’s girlfriend, played by Dina Mayer.

Series regular Katic is currently hard at work on season five in LA, so does the Canadian actress share any traits with her character, Beckett? “I don’t know... if anything I admire her,” she explains. “She has a tremendous amount of integrity. She’s not perfect and in spite of her flaws she tries to do a good thing, and tries to improve and grow.”

Why does she think Castle is still going strong after three years, while other procedural dramas have fallen by the wayside? “There’s a wonderful balance between the humour and the drama. We invest in the characters because of their personal investment in the storylines.”

“It’s very dramatic of course and we give our audience a moment to breathe through the humour, and I think that balance between the two is what draws a lot of people in – and keeps them coming hopefully.”

It doesn’t hurt that she gets to work with Nathan Fillion, star of cult hits Firefly and spin-off Serenity. So, is he as nice a bloke as he seems, or is he a bit of a diva?

“No,” she laughs, clearly still in awe of her co-star even after years of working together.

“It’s funny in the fifth season you’d think you’d be over everyone, but I’m enjoying (working with) him quite a lot now, especially as I think that I learn a lot from him, and he’s quite dear to me.”