On Thin Ice: A Radio 4 Book of the Week: An Explorer's Memoir of Siberia, Surveillance and Survival by Charlie Walker

I woke to a metallic rasp as the small hatch in the cell door swung open. ‘Walker!’ barked a guard. ‘Bweestra!’ Be quick! As I neared the door, a pair of handcuffs were brandished. I presented my wrists through the hatch, palms upward. The dense, gun-grey steel was heavy and cold to the touch.

What comes to mind when you think of Siberia? A world of ice, Siberia occupies a unique place in our imagination: home of the permafrost, rich in natural resource – and infamous for the horrors of the gulag.

In early 2022, Charlie Walker set out to hike 600 miles along Siberia’s frozen rivers. He hoped to cut through the myth to understand who its people are and how they reckon with their haunted past, as well as what the future might hold for this remote corner of our world. But on 24 February, Russia invaded Ukraine, with devastating consequences. What had begun as an adventure swiftly descended into a paranoid nightmare, as Walker began to suspect he was being surveilled by the Russian authorities.

On Thin Ice juxtaposes the harsh beauty of a Siberian winter with a thriller-like series of events that exposes the dark heart of Putin's propaganda machine. It is both the extraordinary record of one man’s walk through the most inhospitable place on earth and a powerful insight into a deeply troubled – and troubling – nation.