Robert Glenister talks about new ITV drama Paranoid and his longtime friendship with co-star Lesley Sharp, best known for Scott & Bailey

Robert Glenister plays Bobby Day, a detective struggling with mental health issues while tackling the darkest case of his career in ITV’s new eight-part thriller Paranoid.

When a young mum is brutally stabbed to death in front of her young son in a busy playground, Bobby and his colleagues spring into action. But they soon uncover evidence which suggests there is more to this murder than meets the eye.

“It’s a conspiracy thriller,” said Robert. “It’s very dark and goes into places that people will find frightening.”

One person who Bobby is desperate to help with his investigation is Lucy Cannonbury, a local woman who witnessed the attack. Yet Lucy is a Quaker and as the investigation unfolds Bobby finds solace in her company and the pair build a close friendship.

Former Hustle star Robert and Scott & Bailey star Lesley Sharp, who plays Lucy, have known each other for many years and the actress revealed that Robert’s involvement was one of the biggest reasons for her joining the cast.

“That’s very nice of her to say that,” said Robert. “Lesley and I have known each other for 30 years!”

Watch Robert Glenister talking about Paranoid, above.

Paranoid starts on Thursday, September 22 at 9pm on ITV