The Hidden City

In the opening minutes of Victor Moreno's latest documentary, you could be forgiven for thinking that you are gazing up at the night sky as, one by one, stars begin to twinkle until an entire galaxy is revealed. In fact, we come to realise we're looking at a wall where something is glittering in the dark. And it's these galaxies and journeys right beneath our feet that he is interested in opening up to us through the course of this meditative and largely dialogue-free film.

The metro tunnels, sewers and caverns below the streets of Madrid could be sets from science-fiction or horror films by Ridley Scott or Andrei Tarkovsky - right down to occasionally glimpsed shadowy figures, some in breathing apparatus - as Moreno and his cinematographer José Ángel Alayón take us on an odyssey with an otherworldly feel. This alien landscape is full of surprises, from the showers of sparks rising as a train runs across rails, to the unexpected intrusion of creatures, including a ghostly barn owl and feral cats, who have made these spaces their home.

The atmosphere is not just created by the images as we glide down seemingly never-ending Kubrickian tunnels or study the physical spaces, but also by the ambient sound, with its industrial droning, its shrieks and clanks all building a symphony of strangeness. There's beauty here but what also feels like the potential for dread - you almost expect a child with long hair to emerge from the shadows.

Moreno's travels give us a sense of the enormity of what lies beneath, unhurried but curious in his progress, even homing in to look at the microscopic monsters we might not realise also make these caverns their home.

This is a poem to the industry of the unseen, from those teeming animals living their own lives in the dark to the more quotidian labour of those who work on and maintain these tunnels so that humans, briefly seen in a train carriage, can be carried from A to B without thinking about it. Moreno's documentary is a show, not tell experience, opening up the possibilities and letting us make of them what we will. It's scope and immersive sensibilities make it perfect for viewing on the big screen - let's hope an enterprising UK distributor takes note - in the meantime, it's playing on the festival circuit and if you get the opportunity to catch it, don't miss it.