Hermione Norris and Martin Clunes will star as a married couple who suspect their child could be a killer in ITV1’s two-part thriller A Mother’s Son.

The hour-long episodes also feature Paul McGann and Alexander Arnold, with filming starting this month (May) for four weeks in London and Suffolk.

‘A Mother’s Son is the story of an ordinary mother tormented by the thought that her son may be capable of murder,’ said Victoria Fea, part of ITV’s Drama Commissioning team alongside Laura Mackie and Sally Haynes, about the programme that is expected to transmit later this year.

‘She’s confronted with this terrifying dilemma and has to ask herself should she go to the police and give him up? She’ll wrestle with this problem throughout what is a very compelling drama.’

Rosie Haleton, played by Spooks star Hermione Norris, is a mum-of-two now on her second marriage to Ben Harley (Doc Martin’s Martin Clunes), who also has two children.

However, when the body of a murdered schoolgirl is found near a town in Suffolk, Rosie suspects her son Jamie (Alexander Arnold) could be involved when she finds a pair of blood-splattered trainers under his bed.

Dismissing her suspicions, she later confides in her ex-husband David (Paul McGann) — who also doesn’t believe their son is responsible, but reluctantly agrees to follow him. Paul discovers that Jamie has been spending time with 19-year-old school drop-out Sean Christie, who was once arrested for sexual assault against a minor. But while Rosie and David begin to suspect Sean instead, their own son’s alibi looks increasingly shaky.

Then Rosie’s suspicions begin to focus on her stepson Rob, who has been playing up for no reason.

Gradually tension mounts in the house, leading to the family holiday being cancelled and arguments escalating. Can they survive the strain?

‘Rosie is in incredibly upset by what she discovers – it’s too awful to believe it could possibly be true. But as the evidence begins to stack up against her son, her turmoil worsens,’ said ITV Studios Executive Producer Myar Craig-Brown.

‘Chris Lang has written a beautifully compelling script and we’re delighted Martin Clunes and Hermione Norris have agreed to play Ben and Rosie.’

Nick Fiaca