Darren Boyd (Spy, Dirk Gently) returns as DC Simon Waterhouse this month for a new two-part story of Case Sensitive, based on the novel The Other Half Lives by Sophie Hannah.

When Ruth Blacksmith leaves her husband for troubled musician Aidan Harper, the love triangle results in a brutal murder. DS Charlie Zailer and her prickly junior, DC Simon Waterhouse, uncover a twisted saga of thwarted ambition and murderous jealousy – whilst wrestling with their own fraught relationship.

The Other Half Lives begins at 9pm on Thursday 12th July on ITV1.

> Buy the complete Case Sensitive boxset on Amazon.

Tell us what’s in store for DC Waterhouse this series…

“The Other Half Lives is based on Sophie Hannah’s book of the same name. It’s about a couple who have recently got together and the girl becomes suspicious about him when he hints at a dark trauma from his past. We learn that no one is what they seem or what they pretend to be.

“People’s motivations are called into question and their pasts are a lot darker than they would perhaps paint on the outside. As a direct result of some of Ruth’s digging, something seriously bad happens and that’s when Zailer and Waterhouse are called in to investigate.”

In this new story we get to focus a little more on Zailer and Waterhouse’s own partnership, which in turn proves to be more than a little tempestuous…

“In the true nature of life repeating itself, we come full circle with their relationship ending up where we started and have to work our way backwards but on a bigger scale this time. In the first series of Case Sensitive something between Zailer and Waterhouse was implied but in the new series it is played out much more in the moment. There are familiar patterns of behaviour but they are less successful. It’s the perfect combination.

“We didn’t want to rinse and repeat the formula set by the first series. Instead we wanted to build upon what we already knew which is the crime, the case the procedure, the puzzles. There is a certain form and structure we have to adhere to in this genre but beyond that the characters themselves have to grow, mess up and try to recover – that’s the universal element. When the crime is eventually solved and the audience turns the TV off, the thing we’re all left with is – what the hell are these two people going to do?”

Can you tell us about the discussions that took place when it came to developing your characters – was it a team effort?

“Olivia and I were involved with the character development from an early stage. The production team at Hat Trick very kindly invited us in to talk about the directions in which we could take the relationship between Zailer and Waterhouse. The opportunity to discuss our thoughts on where to take our characters was incredibly inclusive of them and hopefully the results will speak for themselves.”

Has Sophie Hannah been supportive of the creative process with the adaptation of her books?

“When we adapted Point of Rescue I had never worked with an author who was more willing to hand their work over and be open to questions, suggestions and input. For the new series, the support from Sophie and from fans of her books has been so positive. With any luck that element of trust means we can take that source material, stay faithful to it, whilst making it our own and delivering something that won’t disappoint.”

What’s it like working with Olivia again?

“It’s been fantastic. To be paired with someone of Olivia’s calibre is such a bonus and I couldn’t wish for more. What makes it even more special is there is genuine chemistry, the kind you find in all good friendships when you can come together, have an experience, disappear for a while and then pick up again right from where you left off.

“I was excited about working on the new series; I was looking forward to talking through our characters and filming Zailer and Waterhouse’s development with Olivia. I’m intrigued by their characters because I don’t really get what motivates them. I certainly don’t identify with them and they are definitely frustrating characters but I really like the directions in which that dysfunction takes them.

“I like to think the audience won’t really know how they want the relationship to develop. Often in drama it’s sign-posted quite clearly that the guy should be with the girl, but with these two they could be the best thing that’s ever happened to each other or they could end up killing one another!”

You’ve been very busy in the last year with Holy Flying Circus, Spy and Dirk Gently. Is it satisfying to have such a variety of roles, both comedy and drama?

“It is and I never take it for granted, so I try and ensure I make the right choices. I’ve been doing this for a while now and I really want to make sure it continues. I know what I respond to and what excites me. I’m always drawn to story and character and if I can continue to find ways to be diverse in the choices I make then I won’t bore people and I won’t bore myself!”

Any plans for theatre?

“There have been a couple of roles that have come up in the last year but I’ve yet to find anything I really want to do. It’s been a while since I’ve done any theatre so the prospect is quite scary – but it’s a good scary.”

> Buy the complete Case Sensitive boxset on Amazon.

Are you looking forward to Series 2? Let us know below…