There were steps down into the pit. Will flicked a light switch to the side of them. They looked around, started to speak and fell silent. There, at the far end of the pit, was a door.

‘The workroom?’ Will said, his throat dry. It was completely invisible from above, even with the light on. You would have to actually get down into the pit to see it. He knew at once that this was the reason someone wanted Mrs Swain out of the house. But why?

Matt turned the handle. It was locked. ‘Damnation! We need a key! The garage key ring, Will, is there another key on it?’

Will rummaged around in his pocket and pulled it out. A second, long, Chubb-type key hung next to the one marked “Garage.” His hand shaking, he inserted it in the lock. It turned easily and the door swung open. A single hundred-watt bulb hung from the ceiling, and in its harsh glare the two men saw . . . an orderly and ship-shape workroom.

They gazed around in disbelief. Both had been certain that the missing child would be inside.

With an oath, Will kicked out at a cupboard door. Then, with a cry, he slumped down to the floor and sat with his head in his hands. ‘I really thought . . .’

Matt grasped his shoulder. ‘I know, mate. I did too.’ He looked around. ‘Very well, so we haven’t found Sophie, but I think this is what you were looking for, don’t you?’

Will raised his head and took a proper look at the room. It was about fifteen feet long, quite narrow and had a low ceiling. The fitted benches held expensive power tools — saws, sanders and drills. On one bench was a big vice and several handsaws. On closer inspection, he found drawers full of drill bits, screws, nails and an unused set of wood chisels. The late Mr Swain had obviously been something of a woodworker.

Apart from a walk-in cupboard, there were no other underground rooms, and no way out.

Matt picked up a chisel knife and gingerly ran his finger along the blade. ‘Seems like our Mrs Swain couldn’t bring herself to get rid of all this. And you’d think her husband was here only this morning, it’s so incredibly spick and span.’

Will frowned. ‘A bit hazardous, though, don’t you think? There’s no other exit. I wouldn’t like to be down here if there was a fire, would you?’

‘Perhaps that’s one reason it’s so orderly, and the electrics are all new by the look of it.’ Matt looked around. ‘And, see, two fire extinguishers and a fire blanket, one each end of the workshop. He evidently did all he could to minimise any danger.’