When Sam got back to the police station, he was so overbrimming with ideas that he waylaid the first officer he met in the doorway and asked him to do five different things at once.

"Find out what kind of perfume Helen Thorne was wearing the night she died. And where it came from. And get me a list of all the new-breeds we have on file who can't see—or who have acute senses of smell or something. Anyone who could track a person by scent. And I want an expert on new-breeds. But not Alice Darwin or Dr Petrescu. In fact, I want someone who doesn't even know Alice Darwin or Dr Petrescu. Go to Cambridge if you have to. And I want patrols out tonight. Take one squad down Abingdon Road and one into the city centre."

On this point, at least, the luckless Constable was able to offer some information. "We're headed up there now, sir—on Sergeant Hawthorne's orders. We're the reinforcements."

"Reinforcements?" said Sam, with a pang of alarm. "He's declared war in my absence?"

The Constable looked puzzled. Sam wished he could remember his name, but every one of his men had the same frightened, pink, incompetent face when he was in one of these moods, and it was pointless to try and differentiate them.

"No, sir?" the Constable hazarded. "It's because of the living gargoyle?"

For the first time, Sam looked past the pink-faced Constable, and took in the bustle of the station lobby through the open door behind him. Revolvers were allowed for night patrols—along with pouches, belts, holsters, and rounds of ammunition—and he could see his men struggling with all the unaccustomed equipment.

He strode past the Constable and waded through the throng to the duty officer's desk, snapping at people on the way.

"Wade, that's not your gun. Give it to what's-'is-name. There's another one in the evidence locker on the second floor. Also, don't shoot anyone until I say so. What's going on?"

This was directed at Mrs Hope, the plump, watery-eyed matron whose job it was to see to the welfare of the female prisoners. For all the watery eyes, and her habit of reading romantic novels under the desk when she thought nobody was looking, she was the most capable person Sam knew. He always tried to ensure she was present at the station in some capacity whenever he left the city. It was a form of child-minding. And, since her own child had vanished two years ago, she usually leapt at the chance.

She was quicker on the uptake than the pink-faced Constable. She simply nudged a copy of the Oxford Times towards Sam and went on with her novel.

He picked it up and glared at it. The headline 'Living Gargoyle sighted on the City's Rooftops' glared back.

Some kind of creature had been spotted on the roofs last night. Five witnesses had come forward. Their descriptions varied, but the one which caught Sam's attention was the one who described the creature as 'a gargoyle come to life, only much bigger—with spines up its back, sunken cavities for eyes, and a devil's tail that tapped against the windowpanes as it climbed'.

"It's been spotted again tonight," said Mrs Hope, without looking up from her book. "On the roof of All Souls College. Sergeant Hawthorne took a squad up there half an hour ago."

Sam groaned and passed a weary hand in front of his eyes. "He'll shoot it down before we've had a chance to ask it any questions!"

"Perhaps he thinks its guilt is self-evident," said Mrs Hope. Sam recalled that she had been more watery-eyed than usual when news of the drowned girl had come into the station. "Don't you?"

***

All Souls College was just like the rest of them—tiresomely beautiful, with a wealth of pinnacles, pillars, gables and buttresses that would test the vocabulary of the most enthusiastic student of architecture.

When Sam reached the front gate, with its battlemented tower, he found ladders leaning against the walls, and the outline of worried heads peering down from the roof.

He climbed one of the ladders and located Hawthorne beside the gate tower, kneeling on the slates and peering through a pair of binoculars.

"Where is it?" said Sam, without any preamble. "Did you shoot it?"

Hawthorne didn't look up immediately. Sam got the impression that his spirits were gradually sinking—and it was taking such a long time because they had so far to go. He had looked like a joyful schoolboy playing soldiers a few moments before.

Eventually, he lowered the binoculars and looked up at his commanding officer.

"We saw something about half an hour ago, sir, but it disappeared. Can't 'ave got far, though. I've got men up on the roof of the University Church, and Brasenose, and the Bodleian. We think it must be hiding behind a chimney, or one of those—" He gestured at the chapel of All Souls, which was liberally spiked with pinnacles. "—those pillar-thingies. He'll show 'imself soon enough."

"Is it Helen Thorne's killer?"

Hawthorne gave him a contemptuous look. "Be a bit of a bloody coincidence if it wasn't."

Sam ignored the provocation. He had been ignoring provocations all day. "Some new-breed?"

"Or some new-breed's dad," said Sergeant Hawthorne, spitting over the side of the roof into the quad below. It was meant as a gesture of disgust, but it looked to Sam more like superstition. He thought of countryfolk spitting and touching iron whenever they alluded to the fairies.

Hawthorne thought it was a demon. That could complicate things, especially if he shot it. The new-breeds were desperate to know what the demon race was like. They thought, if they knew who their fathers were, they would know who they were supposed to be. If this creature really was a demon, they wouldn't take kindly to it being killed or locked up. The human race owed them a demon, they would say. The human race had killed their Little Mother.

Sam stared morosely into the dark. The thing that made Oxford particularly suited for rooftop exploration was the fact that most of the college buildings were arranged into quads—a square of buildings around a central lawn. The chapel of All Souls, with its black pinnacles outlined like drawn swords against the lighter black of the sky, formed the north side of this square, directly opposite him, and he was sure that was the only place where the creature could be so well-concealed.

He was tempted to just wait. Something told him a 'living gargoyle' wouldn't be too keen on dawn light. And, even if it didn't burn—or turn to stone—with the rising sun, it would have to come out sooner or later. Even a demon would ned food and water. But...

"Did you put men on the roof of the chapel?" he asked Hawthorne.

"Yes, sir."

"I can't see them."

Hawthorne gave him another withering look. "Well, they're lying in wait, aren't they? I told them to keep their heads down."

"Can you signal to them?"

"'Course," said Hawthorne, rolling his eyes. "I'd hardly forget a thing like that, would I? If I light a match, they're supposed to light a match too, to show they're paying attention. Two matches means they're supposed to come in, and three—"

"Just one will do, for now," said Sam. The lack of motion on the opposite side of the quad was worrying him.

He didn't bother to look at Hawthorne, who was now rattling a box of matches and muttering about timewasters. He was too desperate to see a light flare in the darkness at the opposite end of the quad and tell him everything was all right.

It didn't. When Sam finally turned back to Hawthorne, the Sergeant's match had almost burned down to his fingers, and the expression on his face was a lot less contemptuous.

"Maybe they've fallen asleep," he said, without much conviction.

Sam took a deep, steadying breath. It was some comfort to know that his deep-rooted mistrust of Sergeant Hawthorne was, occasionally, justified.

"I don't think we can risk it, do you? They might need help. Send some men into the chapel and up the vestry stairs. I'll go over the roof on the western side of the quad. With any luck, we'll be able to trap it."

"I'm coming with you," said Hawthorne. He whispered instructions to another nameless, pink-faced Constable, spent a few moments ostentatiously loading his pistol—as though he thought the creature might be watching—and then accompanied Sam across the sloping roof which formed the western side of the quad.

They edged over the wet slates gingerly. Sam was torn between maintaining silence and nagging at Hawthorne to be careful.

They parted to pass round a chimneystack, and Sam lost sight of him for a second. Instead, he looked down, expecting to see a treacherous row of wet slates, and found himself staring at something huge and lithe and muscular, uncurling out of the shadows like a snake.

It launched itself up and tackled him to the slates. Sam felt the back of his head crack against something hard, and splodges of white light blossomed like roses in front of his eyes. He couldn't see the thing on top of him, but it smelled of earth and minerals and stagnant, underground air.

He saw some kind of motion away in the dark to his right, and the creature got off him, whirling round and catching him across the cheek with its tail. It had launched itself at Hawthorne—and Sam heard another thud as he, too, was tackled to the slates.

But Hawthorne had been further down the slope of the roof. If he didn't hang onto something, he could—

There was a scream, and a much nastier thud. Both noises seemed to go on in Sam's head long after they were silenced.

He tried to peer down into the quad below. If Hawthorne had landed in the grass, he could have escaped with just a broken leg. But there was no motion, and motion was the only thing he could have made out through the gloom and the increasing concussion.

There was shouting now, coming from the street below, but it didn't seem to frighten the creature. It turned back to Sam and scrambled on all fours across the slates to get at him.

Sam groped in the guttering and found Hawthorne's revolver. There was barely time to aim, but he prayed he would manage to shoot the thing somewhere non-vital. Even with Hawthorne gone—and possibly dead—the thought of shooting someone wrenched at his stomach.

But the bullet didn't even slow the creature's charge. It tackled him again, this time yanking his legs out from under him, and Sam felt another crack on his head.

He was just sliding out of consciousness—with that horrible, underground smell in his nostrils—when another shadow leapt over him, hit the creature in its chest, and tumbled with it down the sloping roof and into the gloom below.

Sam tried to interpret the noises that followed—cracking bones, maybe? Running footsteps? He was sure he heard the sound of pistols being fired, but it all bled into the overpowering dark which was being drawn over his head.

He only had time to marvel at how clear his glimpse of that second shadow had been. He had only seen it for a moment—in the air, as it leapt over him and hit the creature in its broad, charcoal-grey chest—but it had been blacker than all the rest of the shadows put together, and it had had black ribbons winding, snake-like, up the length of its arms.

What was more, he had recognized it—by its characteristic motions, and not just its face. It shouldn't have been possible to leap out at a monster shyly, but clearly it was if the leaper was Ellini Syal.