Ben got down on his knees, took a deep breath and then poked his head into the shattered pipe. The smell of effluent made his eyes burn. His one consolation was that the castle would have its own private sewerage, so it was only the shit of its owner, henchmen and various staff that he would now have to go crawling through for an unknown distance. He pushed one arm into the pipe. His outstretched hand sank into the three inches of foul-smelling, icy-cold water running along its curved bottom. Then his torso, one leg, then the other, and he was in. Boonzie was a smaller man and would have fitted just a little more comfortably inside the pipe, if comfort was the word. But Ben could make it.

He started to crawl, pushing the lantern along in front of him as he went. The light illuminated the rounded walls of the pipe for a few feet ahead, dissolving into a circle of darkness beyond. A terrible claustrophobia gripped him as he left the hole behind with nowhere to go but forwards. Where he was going, he had no idea. But anywhere was better than here.

And so on he went. Hands and knees, head down, sloshing through the filthy water and the sediment of foulness that was accumulated in the bottom of the pipe, breathing through his mouth to minimise the stench that made him want to puke, trying not to think about Hacker hunting for Grace up there in the castle and what he’d do if he found her.

Ben kept pushing forwards. Twice he found himself verging close to panic, becoming utterly convinced that there was no way out of here, and having to pause while he closed his eyes and steadied his breathing and thought of sunny green hills and wildflower meadows. Get a grip. Boonzie had made it out, and so would he.

Soon afterwards, Ben realised that he could see a faint glimmer of daylight in the circular mouth of the tunnel ahead. Galvanised by the sight, he crawled faster towards it and the daylight grew brighter. It was shining down from a round aperture where the horizontal pipe was jointed at a right angle to a vertical outlet. Step irons were inset into the brickwork and led up to a manhole cover several metres above. Someone had left the iron manhole cover open. There was wonderfully fresh, cold air blowing down it, bringing little snatches of snowflakes that spiralled down and pattered on his face as he raised himself onto his knees and craned his neck upwards to fill his lungs. What must it have felt like for Boonzie, getting his first taste of fresh, beautiful air for the first time in days?