The Sister review: This ghoulish mystery is ideal Halloween viewing

“They’re digging up the woods.”

When Bob (Bertie Carvel) – unkempt, shambolic, creepy – turns up on the doorstep of nice-but-stressed everyman Nathan (Russell Tovey), it’s not welcome news. It isn’t, as you might hope, an invitation to save some magnificent ancient oaks from the vandals running HS2. No, Bob wants Nathan to help him exhume a body. We don’t know yet, in the first of this week’s four episodes of The Sister, exactly how that body came to be buried in the woods, but we do know that it was after a party at which Nathan met a young woman, Elise (Simone Ashley). Elise never returned home, her body was never found, and we know it’s got something to do with Bob and Nathan. There are plenty of suggestions about what happened as the story, told through flashbacks, swings back and forth.

The most disturbing revelation is that after the death of Elise, Nathan stalked her sister Holly (Amrita Acharia), listened to her distress at losing her sister, wooed her, married her and they’re now trying for a family – even as Elise’s corpse lies in a shallow grave just up the road. Holly is bright and lovely, the polar antithesis of Bob, whom she meets briefly. Tovey does well to transmit to the audience the terrible tensions that lie unhappily behind his unremarkable demeanour. Even though he must have done inexplicably monstrous things, somehow we can’t quite believe he is a monster. And if he isn’t, maybe Bob isn’t either...

But what Bob actually is is a crank gone wrong. He first bumped into Nathan at a radio station where Nathan’s an assistant on a phone-in show. Bob was then the rather polished “Professor Bob Morrow”, an expert in the paranormal, able to discuss ghosts in a dispassionate pseudo-scientific manner. Now, though, he believes Elise “is haunting me. She was standing at the foot of my bed. Her mouth was moving.” That is why he’s demanding Nathan’s help to move the remains, because he’s scared, adding helpfully that “it won’t weigh much”. He also threatens Nathan with disclosure to Holly of the gruesome tale if he refuses to help.

The entire proceedings are filmed in horror-movie cliche – dark, rainy nights in shadowy woods with ghoulish dialogue, all ideal for near-Halloween viewing. They forgot to put a pumpkin in the window, but that’s about it. What stops it being risible is the strength of the cast and the very clever, subtle way Neil Cross gets us to believe – not necessarily that poor dead Elise is a ghost, but that Bob thinks she is, and that his convictions are dangerous. So it carries us along, and we too start to wonder about Elise’s ghost, as well as how Elise met her fate. Cross has said that his aim in this adaptation of his novel Buried is “to make viewers sleep with the lights on”. In my case, it certainly worked.

‘The Sister’ continues at 9pm all this week on ITV 1