Based on Robert Macfarlane's 2019 non-fiction bestseller Underland: A Deep Time Journey.

Sandra Hüller’s voiceover guides us through the myriad of extraordinary subterranean spaces beautifully photographed in this stunning documentary.

Mexican cave divers take us through a winding, breathtaking cave barely seen by human eyes in millennia - with its own unique ecosystem thriving in the dark. An enormous ash tree with a cavern opening at its base. A sterile, miles-deep facility in Canada attempts to detect dark matter. Cave artwork dating back to early humans...

Underland weaves an exploration of our human species like no other documentary.