When the nose rose up again the tank was facing uphill but Marius had steered Daisy to the right, towards a small woodland. It had a few broken trees but gave a thicker cover than most of the war-torn woods in the area and the tank couldn’t follow them in there. The donkey had heard the gunfire and broken into a canter for the first time in her life. The trees were close now.

‘Right, right, right, turn right,’ Grimm screamed and the driver passed on the order to the gearsmen. But by the time the runaways were back in his sights they were vanishing into the trees. Silver Hand pulled the trigger. A tree crashed down and made a barrier that even a tank couldn’t cross. ‘Turn left – go around the wood and we’ll catch them coming out of the other side,’ Grimm ordered.

The Whippet tank turned and began to run around the outside of the wood.

In the wood Marius slowed the donkey to a walk. ‘Hurry,’ Aimee urged him.

The boy slid to the ground and handed the reins to her. ‘We might get a head start on Grimm when we’re out of the wood but we could still be in range of that machine gun. We have to stop the tank.’

‘You’re mad,’ she said.

‘Didn’t you say a Whippet crew had to have lots of air vents so they could breathe in all the heat?’ Marius asked as his fingers were busy with the buckles on his backpack.

‘Yes. That’s why they can be stopped with a gas attack.’

Marius nodded and pulled out a grenade. ‘That’s just what I have here.’

‘But as soon as you get near they’ll shoot you,’ Aimee argued.

‘Only if I stand in front of the thing. And if they kill me at least it’ll give you time to get away. Good luck.’

Before Aimee could argue any more, Marius was running along the path through the trees. When he reached the edge of the wood he saw it opened out on to the rough moorland beyond. The tank was just coming around the outside of the wood. He threw himself behind the thickest trunk he could see.

The tank reached the place where it crossed the path. Silver Hand pushed up the hatch to see if the runaways were on the road ahead or still in the wood. While he was at the hatch Marius knew he couldn’t be firing the machine gun. The boy sprinted towards the tank. When he was two seconds away he pulled the pin. In another second he had rolled the grenade under the tank. He had two seconds to turn and get clear.