Stage siren Helen McCrory is convincing as an ice-cool professional woman who melts at a younger man's touch. She plays an aeronautics engineer working on top-secret drones for the British military; words like "suction" and "drag" get bandied around in the first 10 minutes.
On falling for a rangy young Algerian student (Najib Oudghiri) alarm bells ring once she finds he's been reading Islamist websites on his computer. And what are those terrible scars on his midriff?
Polish-born Katarzyna Klimkiewicz puts the Bristol locations to good use, but despite McCrory's anchoring presence the film feels as flimsy as an Airfix model: one false step and you'd crush it.
The suspense never catches fire, and the slo-mo camerawork makes for a "drag" all its own. It just isn't very involving.