‘Don’t be silly. It’s a jolly good wheeze this. We’ll be there and back before you can say Jack Robinson.’

‘Or Albert Ross,’ Grimm replied.

The young pilot threw back his head and laughed a braying, donkey laugh. ‘Nice one, Sergeant. You’re a funny man. Look, slip that parachute on your back – strap your pack to your front. If we can’t land at Cléry you can jump out.’

‘No I can’t.’

‘Nothing to it, old chap. Jump and pull that handle and you’ll float down like a dandelion seed. Ready?’

‘No.’

‘Then off we go.’

27 August 1918: The drovers’ road to Cléry

Aimee said, ‘Today we’ll go just five kilometres.’

‘I’m sorry,’ Marius said with a sigh. ‘I am your enemy. You should not be doing this for me. It is dangerous. I am holding you back. Go home.’

The girl snorted. ‘Maman says the man with the silver hand is dangerous. I am safer here than in Bray. Once he leads them to the enemy spies they will arrest him and I’ll be safe to go home.’

‘Home,’ the German boy echoed.

Aimee smiled. ‘We’ll find this priest in Cléry and you’ll be back in your own country soon.’

‘What will the priest do?’

‘He’ll smuggle you through the British lines and get you to your own army. They’ll make sure you get back safely.’

Marius managed a weak smile. He struggled to his feet and clutched at the bunk bed till his dizziness passed. ‘Five kilometres?’ he said.

‘We’ll stop at every kilometre and rest,’ Aimee promised. ‘There’s an old shepherd’s hut on the drovers’ road where we can rest tonight. Are you ready to go?’ She picked up her pack and carried Marius’s too.

They climbed out of the trench and into the grey morning. Marius shuffled slowly and panted. Even five kilometres would be an effort. The land was flat and the rumble of guns from Peronne was faint. From time to time there was the drone of aircraft from the Somme airfield. Some brave skylark rose in the air and sang.

They met no one on the forgotten road. They were fleeing from the man with the silver hand, yet they never looked back. If they had, they might have seen the follower in the long black cloak. He had no trouble keeping up with Marius’s slow pace. He hung back. There was no cover on the flat and treeless plain. If they had turned around he’d have had to scramble into a ditch.

So, in that vast flatness, when the aircraft came there was nowhere for Marius and Aimee to hide.

The RE8 plane lumbered into the air with the ease of a winged elephant. Pilot Officer Brand kept low. ‘If we climb above the clouds we could be jumped on by a German fighter or ten.’