‘Nothing to report, boss,’ she said sleepily. ‘Unless you count several tom cats and a couple of hedgehogs.’ She handed him the night vision binoculars. ‘Don’t forget, mind, no wading in alone if you see someone. Bryn Owen knows what we are up to, and if we need the Fenland Constabulary’s help, we ask for it.’

Matt smiled into the darkness. ‘I know the drill, Liz, and I promise I’ll follow it to the letter.’

‘Why don’t I believe that?’ she whispered back.

‘Can’t think.’ Matt pecked her cheek. ‘Now, go and get some sleep, but keep your mobile with you, just in case.’

Liz slipped silently out into the night.

* * *

Matt was an hour into his shift when he heard the noise. It was a metallic sound, a single note, like someone striking a steel drum.

He crept cautiously out of the summerhouse and listened, trying to ascertain where the sound had come from. All he could hear were the sounds of the night — the breeze blowing about a plastic bag caught in the hedgerow, the quiet knock of wood on wood from Emilia’s badly fitting greenhouse door, the call of a night bird somewhere out on the marsh. And something else.

He was not alone in that garden.

The wind dropped and an eerie stillness settled over Whisper Fen.

Matt crept closer to the hedge and squinted into the darkness, trying to discern any sign of movement.

Ahead, in a narrow passageway between the house and the coal shed, was a shadow, moving almost imperceptibly towards the rear of the building. Matt took his heavy Maglite torch from his pocket and braced himself.

As soon as the shape reached the far end of the alleyway, Matt broke cover and ran. He hesitated at the corner of the house in case the villain was waiting for him and was just in time to see the dark figure move swiftly towards the back gate.

Matt crashed through the gate and almost cannoned straight into him. A vicious blow to the side of his head knocked him to the ground, stunning him momentarily. When he staggered to his feet, still groggy, his assailant was already out in the lane and running.

With no earthly chance of catching him, Matt picked up his torch and made his way to the front of the house. He sank down on to Emilia’s garden seat, took out his mobile and called the police station. They would never get to the lane before his attacker vanished completely, but it was worth a try.

His head felt as though he had run full pelt into a brick wall and a wave of nausea swept through him. He told himself to ring Liz, but he didn’t want to alarm her. While he waited for the sickness to pass, he tried to recall if he had noticed anything about the person who had hit him. Finally, he rang home.