There was smoke drifting up through the doorway in the little circular turret at the corner of the tower. The steeple was acting like a chimney, sucking the smoke out of the church, even though they had lit the fire down at the other end by the altar. Ollie had read enough about fires to know that the smoke would kill you before the flames ever got to you. He tugged off his jumper and wrapped it round the lower half of his face, covering his nose and mouth. He had a knitted cap stuffed into the back pocket of his jeans and he jammed it on, leaving just a narrow strip for his eyes. He walked over to the doorway and peered inside. The smoke was making it very hard to see anything. He backed away then leant over the wall.

‘Lob me up my torch,’ he called down to Ebenezer. Ebenezer was a brilliant shot, and his throwing arm was strong. He threw the torch up so that it reached its apex right in front of Ollie, who simply had to pluck it out of the air. It was fully wound up and he snapped on the beam. Returned to the smoke-filled doorway.

He paused a moment and then filled his lungs with as much air as they would hold. If he could hold his breath all the way down and back he’d be safe. He plunged inside.

Smoke was climbing the stairs in a thick column. His eyes were already stinging. He forced himself down the spiral staircase, feeling his way, as, despite the torch, he couldn’t see anything. Round and round he went, down and down, his lungs starting to burn. If he slipped and fell he doubted he’d ever get up again. And then he stumbled as he reached the bottom and there were no more steps. He crashed into the wall. Steadied himself. Chest tight. Eyes sore and watery.

Where was the cupboard Lettis had written about? Where was Lettis?

He groped around, feeling the brickwork, trying to get the layout into his head. It was under the stairs, she had said. Then he discovered a pocket of clear air that the circulating smoke was avoiding as it went into a swirling eddy before being sucked up the stairway.

Ollie moved into the clear patch, emptied his lungs with a groan and risked taking a breath. The air tasted sour and it clawed at his throat, but he held it in, hoping it would be enough to take him back up to the top.

And then he saw it. A small cupboard door, tucked under the stairs, too small for a person to fit through, surely. There was nothing else down here, though, and his air supply was rapidly running out. Already his lungs were filling with carbon dioxide again.