Jenny knew what a hassle it was to get the tyre off the back wheel, repair and replace it, and she was already reaching that state of tiredness where everything felt like a major task. But there was nothing else for it. Sighing, she flipped the quick-release lever and dropped the wheel on the ground. The forks of the bike pointed into the air in an undignified posture, like a dead animal on its back.

She was reminded of a photograph that had been taken at the height of the panic over mad cow disease. It had shown a slaughtered British Holstein cow, a huge animal with its stomach bloated, its vast udder shiny and leaking a dribble of milk, and its four stiff legs pointing ludicrously to the sky. The cow had been waiting its turn to be rolled into an incinerator. Its photograph had been on the front of leaflets that Jenny had helped to distribute, and she had seen it so many times that the details had stayed with her ever since, along with other images of things that had been done to animals.

Automatically, she patted the pouch she wore round her waist, to make sure it was still there. Soon, she would have to decide what to do with what it contained.

Jenny shivered. The weather had changed, and the evening would be cold. The feathery stems of cotton grass created patches of golden mist close to the ground. They hovered just above the heather, moving in the wind like live creatures stirring in their nests.

It was the noise of the wind in Jenny’s ears that covered the soft sound of footsteps until the walker was only a few feet behind her.

In half an hour, Mark was due to go off duty. Owen had given him exact instructions for his first solo patrol – a pass across the face of Ringham and a descent into the valley on the far side, where the moor turned into farmland. There he was to take a look at the walls and stiles and signposts for recent damage, and have a scout around for the worst of the litter left by hikers.

On the way back, he should have a glance at the Nine Virgins to see that the ancient monument was no more scarred than usual; have a word, perhaps, with any campers foolhardy enough to have pitched their tents in the woods. Mark couldn’t imagine why anybody would want to camp on the moor at any time of the year, let alone in November. But still they did it. And they were breaking the law when they did.