Imagine a blisteringly hot August afternoon. Moscow in summer is like a pressure cooker, shimmering with heat, its residents ready to explode. Sirens echo off Stalinist skyscrapers. Fuming policemen swagger across the broad boulevards, their truncheons knocking against their jackboots. Me? I’m in air conditioned cool, heading out of town in a convoy of top of the line Range Rovers. My host is Russia’s chicken tsar Dmitri Denisovich, an oligarch about whom there is something magnetic, something mercurial and something seriously shady too.

Thirty minutes later the forest began to close in around us, looming so close to the road that it seemed to cut off the light. Family cars pulled onto the gravel shoulder, parents and children with wicker baskets vanishing between the massed conifers. Soon we too turned off the highway and onto a dirt track. I peered ahead in the hope of catching sight of a weathered wooden villa with high balconies and intricate fretwork. I imagined – thanks to Chekhov – long walks in its apple orchard with the scent of hay and the sound of a piano in the air. Instead I saw only deadening pinewoods.

‘Is this the road to your dacha?’ I asked.

‘My dacha?’ replied Dmitri, calm again, playing with the word and me. ‘For sure, you see no dacha at all.’

I recalled my London friend warning me that Dmitri had wildness in him, flooding his veins, beating under his skin, and that I had to be careful. On the seat beside him I sensed more than his capriciousness, and pongy aftershave. ‘First we make fun,’ he went on, enjoying his control of the situation, nodding at his bodyguard, ‘Is why we need Vasya.’

Our convoy stopped in in the middle of nowhere and five strangers emerged from the other Range Rover. I couldn’t tell who belonged to whom but I guessed the young woman might have been his wife or partner, if he was married. Dmitri made no introductions. No one met my eye. Vasya – who I’d imagined carried a pistol – opened the lead Range Rover’s tailgate and took out four empty yellow tubs. As he handed them to the group, Dmitri issued instructions in Russian. All responded with a respectful “Sudar'”. The Tsarist “Sire”. Vasya then unloaded a coil of rope, black bin bags, a hose … and half-a-dozen Kalashnikovs. Dmitri revelled in my alarm. ‘Like I say, if I tell too much, I must kill you,’ he repeated with his broken rock laugh.

Around us the trees lay at wild angles like giant spillikins, the oldest pines having fallen, rotted and fed the saplings that sprouted on their remains. Vasya vanished between them with the guns as the group split into pairs. In the open glades the air was wild with heat, cut through by darting horseflies. Dimitri and I walked together between the shimmering streaks of brightness and patches of shade, buckets in hand, with heads down.

Every Russian child knows the names of a dozen forest mushrooms. Boys and girls are said to be able follow the rich musty fragrance into the darkest glades, and to recognise the tastiest, rarest and most poisonous fungi. I, on the other hand, couldn’t stop thinking about the guns.

‘Lisichki!’ Dmitri cried almost at once, spotting a cluster of yellow ‘little vixen’ chanterelle. ‘My favourite.’

As we wandered further away from the vehicles, the frowning trees closed in again to shut out the sky. No sound disturbed the vast silence, apart from distant voices calling out their discoveries. It was hot and sweaty work, raking through the mouldering leaves, stumbling over fallen trunks, my eyes peeled for either honey-coloured opyonok or an imagined assassin…

…Over the next hour we described a broad circle through the woods, arriving together in a sun-chequered clearing as if on cue. Dmitri inspected the others’ spoils with approval. In the buckets were five or six kilos of chunky ceps, yellow chanterelles and brightly-capped birch boletes with grey-flecked stalks. A good haul for the time of year. Then Vasya handed out the guns. He gave the last AK-47 to Dmitri. Of all the men I alone did not have one. Beads of sweat rolled down my back. I looked around for cover, judging which way to run. The forest was silent apart from the babble of a nearby stream. Pointlessly I checked that my passport was in my pocket.

‘Now for fun,’ said Dmitri. He lifted the Kalashnikov, and passed it to me. Only now did I see the rope, strung between the treetops and suspending a dozen swollen bin bags high above our heads. The woman started to laugh with sudden, girlish excitement. The men snuffed out their cigarettes and jostled for position beneath the bags. On a signal from Dmitri, they started to shoot. The woods crackled with rapid gunfire and in an instant the bags exploded, showering the party with cool fresh water, which had been syphoned from the stream by Vasya. Terrified birds took flight from the surrounding trees. Wood splinters and broken branches tumbled onto the forest floor. The air stank of cordite and pine sap.

‘To God’s great Russia,’ shouted Dmitri above the laughter, in a kind of blessing, soaked to the skin like the rest of us, ‘May it never die.’

‘Pravda Ha Ha’ is published worldwide by Bloomsbury. In the UK it was chosen as a Travel Book of the Year by the Financial Times.