Alastair Lee’s adventure documentary is meant to be about an attempt by the ultra-high-achieving blind rock climber Jesse Dufton to scale the Old Man of Hoy, a formidable 450ft sea stack off Orkney. Born with a degenerative eye condition, Dufton can only distinguish between light and dark. Unusually for a non-sighted climber in a team of two, he is the lead, which means he goes first, taking the risks, placing the gear into cracks in the rock, clipping in the ropes. His climbing partner is his wife, Molly Thompson. And here’s where the film really takes off, as a tender and moving portrait of a very English marriage. Dufton and Thompson are unsentimental plain-speakers: after the intoxicating thrill of a climb, don’t expect a high five, fist bump or cry of “Awesome!” The most you can hope for is a gentle: “Ace. Good work, matey.” But they are so obviously head over heels with each other: you see it in the gentle touch of her hand in the space between his shoulder blades at an indoor climbing wall; he knows exactly which way she wants him to move. The pair met at university, when Dufton still had a little sight remaining. The only time he lingers on his blindness is talking about no longer being able to see his wife’s face. Watching them climb the Old Man of Hoy, picking their way up a vertical face, a 100ft drop below them, is scarier than any horror film. Five hours into their trek, they’re only halfway up and things begin to get a bit hairy. But you sense this couple can get through anything together. • Climbing Blind is due for release in the UK on 20 March, and will be available for streaming on Vimeo on 20 May.