“At least it’s not difficult sealing off the site,” said Banbury. “As far as I’m aware, there are only four sets of keys into the mortuary, including Finch’s own. Giles, can you see if he has a set on him?”

Kershaw flicked a lick of blond hair from his eyes and knelt beside the body. He carefully detached a pair of keys, one Chubb, one Yale, from the pathologist’s pocket and placed them in a plastic bag. As the unit had no photographer of its own, Banbury photographed the body’s position and marked it. All that remained was for Finch to be lifted onto his own table.

“Well, we’ve got an instrument of death, but I don’t think this was quite the simple accident it appears to be,” said Banbury.

“What do you mean?” Longbright studied his face for clues.

“Giles, is it okay to pick up the fan blade?”

“So long as you’ve grid-marked it.”

Kershaw raised the aluminium spinner by its fin. “The central pin holding the propeller to the shaft has sheared. Looks to me like a slow stress fracture, and they take a long time to develop. You can see the thing was spinning anticlockwise because this edge‘-he pointed to the top rim of the right-hand blade-’is covered by a thick layer of dirt, and so is the opposite side of the other blade. There’s a dent on the very end, which I’m willing to bet will match the crescent dent on the fan housing.” He pointed upward. “You can see the mark where it flew off from down here. So, let’s piece the event together and find out what’s wrong.”

Banbury had a commonsense attitude to police work that the others sometimes lacked. You could see cogs turning in his head. “I know that the fan housing fell off some weeks earlier-it’s over there on its side, under Finch’s desk, waiting to be reattached. Finch complained about it to anyone who would listen, and wasn’t happy about having to operate beneath the uncovered blades. But I suppose he needed the air on whenever he was working. The pin finally snapped, and with nothing to stop it, the spinning blade dropped, bouncing against the housing, which would have sent it down into the room still spinning, but at an angle. But Finch was standing right underneath-we know that by the way in which he’s fallen-so how on earth could he get hit by a fan blade that was veering away from him? That’s one point. This is the other.”

He indicated the two clean edges of the blade. “If the blade is spinning counterclockwise, it would be one of the two dirty edges that would hit him. However, as you can both see, the rims of dirt on either blade have not been disturbed, nor is there a dirt-mark on Oswald’s neck. So, although this thing is the only potential weapon in the room that is likely to have caused such a bruise, it seems it didn’t do so. If Finch wasn’t killed by a falling fan, what did kill him?”

He led them over to the door handle. “The lock hasn’t been forced. If someone came here looking for trouble without having the right keys, Finch would have had to let them in himself. For any assailant, the obvious weapons couldn’t be more visible.” He pointed to the glass cabinets where an assortment of scalpels and knives stood in their racks. “He always returned them there after they’d cooled down from the steriliser. Suppose he somehow bashed himself on the furniture and suffered a trauma?”

“You’re thinking he underwent a natural termination in the form of a cardiac arrest? It would make life easier to think so, but there’s no sign of cyanosis, no muscle tension, no dilation of his pupils.” Kershaw knew that once accident, natural death and suicide were ruled out, only homicide remained. It was a conclusion he would be reluctant to reach. “So what was it?”

In the faintly humming room, beneath bleach-white lights, the three officers stood looking about themselves, and wondered. “He was argumentative and frail,” said Longbright. “Suppose he fought with someone, and they lost their temper? All of us have wanted to thump him at one time or another. Some have more reason to do so than others.”

Both she and Banbury turned to look at Giles Kershaw.

“I detest motorways,” Bryant complained for the third time as he attempted to realign his overcoat buttons. “How on earth are you supposed to know where you get off?”

“There are several absolutely enormous signposts along the way,” May pointed out.

Bryant squinted through the windscreen. “Did I miss Taunton?”

“You slept through Taunton and Exeter,” said May. “We’re about to come off the M5 onto the A38. Why this spiritualists’ convention has to take place in such a remote corner of the country is beyond me.”

“It’s an area perfectly attuned to the mysteries of the netherworld,” replied Bryant. “You clearly have no historical appreciation of the countryside.” This was a bit rich coming from a man who only left central London to attend funerals, and complained bitterly every time he did so. “There’s not much traffic, is there?”

“The journey’s taking longer than I thought. Sensible people have probably been listening to the weather forecast. The Devon and Cornwall Police have been issuing warnings to stay indoors for the past hour. Damn, I’ve missed a sign now,” May rubbed his forehead wearily. “I was looking out for Buckfast and Ashburton.”

Snow had been falling fast and hard for more than two hours, blotting the pallid sky and sheening the grey, half-empty road. Across the light woodland, a village spire flickered through falling flakes.

“I’ll map-read for a while.” Bryant dragged the ancient guide out of his overcoat and leafed through it without recourse to his reading glasses. “I knew you would eventually need me to get us there.”

“I’ve been meaning to ask you for years, Arthur, but we so rarely get the chance to talk like this. Where did your fascination with the occult and alternative religions start? I mean, all that stuff you believe in, psychogeography, pagan cabals, astromancy, witchcraft and predestination, where did it all come from? You’re from sensible working-class East End stock. I’m sure your mother didn’t have time for such things.”

“That’s the paradox,” said Bryant, popping a Milk Bottle into his mouth and chewing pensively. “East-Enders are a prosaic but superstitious lot. My father would never bring a budgerigar into the house or put his boots on the bed, or take photographs of babies, or hand a knife to a friend, or touch a Welshman…‘

“Wait, what were those things supposed to signify?”

“Well, all house birds except canaries were considered bad luck because sailors left them at home while they were at sea. If they didn’t return to claim them, the birds acted as reminders of lost husbands. Boots on a bed meant a death in the family, because that was how you chose the burial boots, by laying them out. Photographing babies was tempting fate when they were so likely to die before the age of two, and knives cut friendship.”

“And not touching a Welshman?”

“Oh, he just couldn’t stand them. Take this next exit.”

“Are you sure? I thought we were supposed to stay on the motorway until it ended.”

“You wanted to bypass Totnes.”

“No, I said the A38 did that anyway.”

Earlier they had glimpsed the pale ribbon of the sea, but now to their right was the bleak vastness of Dartmoor, where the frosted roads dwindled into twisting corridors of hedge, and coasting winds could buffet snow into mazelike drifts. The dark hills had faded beneath an unblemished whiteness of freshly ironed tablecloths. Fat snowflakes almost blotted out the slate sky.

Bryant had been a good passenger for most of the journey by dint of the fact that he had been asleep, but now he was wide-eyed, aching and fidgety with boredom. “It was difficult not to seek alternative meanings in our house,” he continued. “My devout grandmother lost all three of her sons in the Great War, and my aunts lost their children in the flu pandemic that followed. Then, just when we all seemed to be recovering in the intervening years, my uncles were drowned at sea and we were bombed out of the family house in Bethnal Green. Where did our devotion to God get us? If you ask such questions as a child and don’t receive any satisfactory answers, you start to look for other means of proof.”