Olafur Arnalds’ score for Let The Right One In, soars over and above most of this production. It’s only Martin Quinn in the central role of Oskar, and the skilled movement from the rest of the cast that’s anywhere near as vivifying.

In this stage adaptation of the vampire novel by John Ajvide Lindqvist, the action takes place around a joyless climbing frame in an otherwise empty, beautifully lit wooded area which happens to be the site of a spate of brutal, bloody murders. This spot is where the bullied Oskar meets outsider Eli as he imagines enacting a violent revenge on his aggressors.

Eli appears in the freezing cold without a coat, pretty and alluring, she comes with mystery and a bad smell.  Oskar, sweetheart that he is, doesn’t mind the stench. The stinky new girl won’t win him much status among his peers but he falls hard for Eli nonetheless and truly wins over the crowd when he decides to love her regardless of her ambiguous gender.

There’s a lot about their relationship however, that doesn’t convince. Rebecca Benson as Eli goes for otherworldly but hits robotic and disastrously, she stays with it. Gratingly measured in tone she delivers each line like she’s throwing knives at Oskar, each one designed to challenge and excite him. But Oskar’s so kindhearted and unassuming, it’s hard to see why he’s fall for someone who doesn’t show that she cares for him. The gender thing feels like a bizarre add-on under John Tiffany’s direction. It’s thrown into the dialogue rather than allowed to emerge from the characters.

While Eli and Oskar are supposedly falling for each other, more and more bodies are found and Eli has a complicated, indirect involvement with the murders. Her relationship with the man we assume is her father is hashed out, as is Oskar’s relationship with his mother. Both bonds between the children and adults are depicted with stylistic movement which explains their awkward mix of closeness and heightened awareness. Oskar faces his own trials with relentless bullies and adults who miss the opportunity to really help him.

Jack Thorne gets some kudos for thinking broadly with his adaptation as does John Tiffany for his great visual ideas but they’re still overshadowed by the combination of Olafur Arnauds’ music and Christine Jones’ set design which is stingingly satiating. Arnalds’ soundtrack places us in a small town of full of heightened paranoia and casual criminality. He amps this up as the brutality of the action and interaction increases. Jones’ set remains a cool, alluring winter hideout throughout, but one that pulls you into the huddled groups that form onstage or leaves you alone and isolated in snow like Oskar.

Let The Right One In is a smooth production with a fantastic soundtrack that should have had a more convincing relationship between the leads.

Let The Right One In runs at Royal Court until 21st December.