Anyone who read Ian McEwan's The Child in Time at the time of its 1987 publication and not picked it up since is unlikely to have forgotten the bone-chilling opening scene. A father takes his three-year-old daughter to the supermarket near their home and after being momentarily distracted at the check-out loses sight of his child who suddenly goes missing, presumed kidnapped.

In this one-off drama, that father, Stephen Lewis (a successful children's author), is made flesh in the familiar frame of Benedict Cumberbatch. After the alarm is raised, he has to trudge home to share the appalling news with his soon-to-be devastated wife Julie, played by Kelly Macdonald. We know that Julie is devastated as she cries quite a bit when Stephen comes home, but for the rest of the 90-minute drama, Macdonald plays Julie as a paragon of calm, seemingly coming to terms with the fact that their daughter may be out of their lives forever, a child locked in time destined to always be a yellow-coated three-year-old in their minds.

Sadly, this sense of calm is more likely down to the fact that Macdonald has never especially been renowned for her wide emotional range. Cumberbatch has more success with displaying the trauma across his face and within his eyes, but even he has a 'just getting on with it' air in scenes which you might assume (falsely) must have taken place prior to the kidnapping, so relaxed is his chat and untroubled is his demeanour.

But the story is not simply about one child who goes missing on an ordinary Saturday morning. It's a mediation on time and memory, about the things we choose to remember and those we want to forget but can't. It's also about the loss of innocence and how the adult world crushes the playful aspects of our child-like state. This is most obviously tackled in the character of Charles Darke (Stephen Campbell Moore), both Stephen's best friend and his publisher, and also a junior Minister of a government that's busy pushing through legislation which appears set to drag the notion of childcare back to a more arcane age. Charles quits all his jobs and retreats to the country to apparently regain his inner schoolboy again, playing solo games of soldiers and building dens, but this attempt to reclaim innocence tips him over the edge into a full-on breakdown.

In squeezing an acclaimed novel into a 90-minute film, screenwriter Stephen Butchard and director Julian Farino obviously had to make their own choices. But it's curious that Charles' wife Thelma (Saskia Reeves) is so sidelined here as simply a passive observer of her husband's psychological decline when in the book her character is a quantum physicist with theories on space and time which related to the story's deeper existential layers and helped supplement McEwan's flourishes of magic realism flourishes. Even one conversation between Stephen and Thelma could have opened up the drama and given her more of a significant role; instead we see Stephen learning how to play the piano and possibly having a post break-up thing with a primary school head.

The Child in Time feels like a lost opportunity to have made a classic slice of 80s British fiction further enriched for today's audience. But with acting that occasionally leaves you flummoxed and an oppressive score that demands you feel sad when the stark horror should leave its own mark, the viewer is also likely to feel a little lost.

The Child in Time is on BBC One, Sun 24 Sep, 9pm.