Kate charged at an SUV waiting behind the lorry. A frightened man and woman stared at her in horror. ‘Get out!’ she yelled. She ran to the driver’s side. The man locked the door.

Kate smashed the window, unlocked the door and yanked him out. His wife screamed. As the man tried to fight back, she punched him in the stomach hard enough to wind him. The woman was out of the car now, reaching for her child, who was screaming in the back.

Kate got into the driver’s seat as the lorries and cars around them hooted in protest. No one got out to help the stricken family.

As soon as Stuart was in, Kate turned the car around, slamming carelessly into the tunnel front and back as she made the tight turn. She accelerated away. As she did so, the jeep sent to pursue them smashed into the side of the stricken Lada they had abandoned.

But she had wedged it sufficiently that it did not dislodge. ‘What’s happening?’ Kate asked Stuart.

He turned around. ‘They’re shunting the Lada,’ he said hesitantly. ‘Hitting harder.’

The tyres of the SUV were flat and Kate had to fight the steering wheel, which pulled hard to the right.

They burst free of the tunnel.

Kate closed her mind to everything but the twists and turns of the road ahead of her. She was doing seventy or eighty on a route in which forty was already much too fast.

Every time Stuart tore his eyes from their pursuers, he braced at the road hurtling towards them.

They passed in and out of tunnels. And still the queue of traffic on the other side was solid and stationary.

‘They’re closing,’ Stuart said, failing to keep the panic from his voice.

‘How many?’

‘One jeep.’ She waited. ‘No, two,’ he said.

They entered another tunnel. Kate hit a pothole, lost control of the car. It smashed into the wall, bounced back into the line of vehicles opposite and hit the wall a second time. One of the tyres had burst.

Within yards, the screech of metal on tarmac was piercing. Kate lost control of the car again and it slammed into the line of traffic coming the other way, spun once and was again wedged between a truck and the wall.

Kate needed to give Stuart no instruction this time. He clambered out behind her. Up ahead, she could see the barrier finally of the Georgian border. ‘Run,’ she said.

They sprinted out of the tunnel. It was two hundred metres at most to the barrier. Kate glanced behind her as the lead jeep shunted the car blocking its passage.

Stuart tripped. She doubled back to help him. He tried to get up, but yelled in pain. ‘My ankle.’ He was groaning. She put his arm around her shoulder and yanked him to his feet. ‘No,’ he said, hobbling in agony.

‘I’ll carry you!’

He crouched down on his good leg and tugged her down towards him, his face close to her own. His gaze was steely. ‘If you stay, we will both die. Go!’