Of course there had to be a spanner in the works. The black-painted door of the grand house in Curzon Place closed smoothly but firmly in his face and William stood defeated, mouth still open, shoulders yet to sag. A grim countenance regarded him balefully from the ornate doorknob. William waited a moment, in the Dickensian hope that it might morph into something ghastly and give him something to fight, but all he got was intransigent brass. Mr Inglis, he had been informed dourly by a stony-faced housekeeper, is not at home.

William didn't believe it for a moment. He'd walked the two miles from the railway station in a blaze of purpose, all the strength of the young navvy's blood turned to vengeful determination inside him. He'd smiled viciously at the housekeeper, thinking he would probably have her for dessert. And now this. It was late, lights burned at all the windows of the handsome house, and Inglis was probably ensconced with his port and his hatefulness and his impermeable smug satisfaction, thinking up more devastating witticisms like the one with which he'd derided poor dead William's poetry. But there was nothing he could do. He still heard Angelus's laughter at his expression the first time he attempted to gate-crash, and humiliation was an effective teacher. So he stood stupidly on the porch for a moment longer, the grimly familiar feeling of not being invited grinding in his stomach, then wheeled around and marched back into the street. Frustration and thwarted purpose left him with all his determination and no plan, so he hung a left on a whim and strode off. He retrieved the spikes from the back pocket of his trousers, where he'd hidden them for appearance's sake throughout the encounter with the housekeeper, and appreciated their reassuring weight in his hands. There was only one man he had really wanted to use them on, but if needs must there were other past wrongs he could set about righting. As luck would have it, he was heading in the direction of Hardenhuish Square. How delicious. Things had definitely been wrong there.

As Arthur emerged onto Hardenhuish Square, he couldn't help feeling that something was wrong. The bright lights and even paving, the trim gardens hemmed in with neat iron palings, should all have been a comfort: he'd grown chilled during his walk from the party, and it was no fault of the mild evening weather. The route he had chosen avoided the darkest streets, narrowest alleys, and loneliest fringes of Regent's Park, but he'd found himself faltering as the gut-gnawing misery that had claimed him at the party spread chilly through his limbs. He had turned up his collar, shivering, glancing vulnerably over his shoulder, and had been unable to stop thinking about that poor vanished poet. Were William's last moments like this? Arthur couldn't swallow the suicide theory. The social circle was far too happy with it: they seemed to think it made a neat coda to a life they'd seen as a pathetic joke. It seemed all wrong to Arthur. Real poets, he felt, do not kill themselves. Real poets have to see how the story ends.

It would be a shame, though, if the story ended in some unlit north London street for want of a cab fare. Henry Inglis, insufferable man that he was, had his own carriage and cabman, which were a sight more than Arthur could aspire to. Arthur's uncle had told him once that Inglis was one of the group of one thousand persons who make the empire great. His father had been that Heath Galton Inglis who mesmerised the House of Commons with electrifying speeches on the Reform Bill; his brother was the Chief Commissioner for a vast district of India; and his mother had been a society beauty noted for her philanthropy. What Henry himself had done to contribute to this honour roll, Arthur could not recall. Indeed, he began to suspect that information had never been included in his uncle's account. But the carriage was an indisputable advantage: it meant that, when Inglis had finished promenading and making anodyne observations on the beauty of the sunset, he could sweep Cecily up into the cab and convey her home in glorious comfort, while Arthur plodded the dismal streets until his legs felt like stumps.

It was quite dark now, and he was still a good half-hour from home, but Arthur had hoped to find some reassurance in the familiar prospect of Hardenhuish Square. The fact that even this well-known place failed to comfort him almost made Arthur wish for a dose of the London fog that, as winter came on, crept staunchly across the city, as though the ghost of the foul Thames itself had risen and stalked the streets. At least it would have justified the sick feeling in his stomach. If London would behave in a properly sinister fashion, he'd understand it better. It was the city's damned ambiguity that threw him off.

Hardenhuish Square, and more specifically Underwood House, could have been the general headquarters of London ambiguity. Arthur couldn't put his finger on just what was uncanny about the place, but if he'd had to try he'd have gestured in Miss Addams's direction. Cecily really was a singular young woman. He couldn't very well call on her uninvited, though he'd often passed the house with some vague hope of a chance encounter. There was nothing seamy about that, he told himself: after all, the place seemed to be the fulcrum of a great deal of unaccountable activity. He'd been surprised alternately by the odd hours at which Miss Addams seemed to receive her visitors, and by the fact that he'd often passed and found the curtains drawn at high noon. Moreover, though he had spent some months in London now, he had yet to encounter or even hear of any relative of Cecily's.

He could have asked her about it all, perhaps, but whenever he summoned up the courage to speak to her he found his throat constricting and his mind emptying. Someone had introduced them to one another as fellow lovers of travel, and he'd begun trying to dress up his time as a doctor's skivvy in Austria or tending to the accursed whalers as breathtaking adventures. His cheeks had burned as he saw her polite expression glaze over, and had only been able to extract from her that she'd been to the Crimea and to France. Her inaccessible eccentricity was part of her allure, Arthur supposed. When he compared her to the girls at home with whom he might make his future, they seemed dull hedge sparrows and she an exotic cardinal. Her enigmatic charm must have bewitched him. On the other hand, he'd been at sea for months.

As he might have suspected, there was even now a carriage pulled up at Underwood House, though it was terribly late for visitors. Approaching, Arthur glimpsed figures standing in the porch: a tall, thickset man executing a grandiose series of hand-gestures, and a small dark woman, her expression impossible to work out at this distance, standing stiffly still. Cecily? From the other side of the street, Arthur peered at the carriage. With a shock of recognition, he narrowed his eyes. My god: he knew that hunched, stolid driver and that showy cab. Could it be – was it –?

Inglis's carriage. William recognised it from a long way off. He had an aggrieved recollection of a past episode when he'd been convinced the cad had tried to run him over in it, though Inglis had mirthfully explained the whole business away as an unfortunate mishap with a skittish horse. Seeing the blasted thing now made the knot of anger in his gut grow; the self-important bastard was here, on Cecily's street, at Cecily's house. William stopped walking.

It was only then that Arthur noticed the fifth person in the square. The stranger broke from the grainy shadows that pooled out from an alley leading off to the east, strode a few paces, then halted abruptly. Arthur squinted. He himself was still rather far off, with the carriage between them partially hiding him from the stranger's line of vision, but something about the other man looked compellingly familiar. And something made him want to stay exactly where he was. He stopped just as the other man did, and regarded the scene.

The sounds of conversation carried faintly in the mild, still air, though it was impossible to make out the words, and, from Arthur's obstructed vantage point, Cecily's expression remained unreadable. He stared, straining his eyes, at the stranger who had emerged from the alley, but failed to distinguish his shadow-cloaked features. Like Arthur, he appeared to be considering the figures in the porch. Arthur could just make out the uneven silhouette of his unkempt hair, and the bulky, untailored lines of his clothes He appeared to hold something clutched in his left fist. For a moment Arthur felt as though he had a cheap seat at the theatre, and was watching an actor standing in the wings, waiting to take the stage. The figure had that aspect of poise and anticipation, of quiet preparation to step into a role. Maybe even nerves: he seemed to be shifting his weight from foot to foot, as though steeling himself. Then, as abruptly as he'd stopped, the figure again began to move. He closed rapidly on Miss Addams's house.

The sounds of conversation stopped. Then, loud enough to carry to Arthur's ears, came Cecily's astonished voice: "William?"

Cecily's mouth was a perfect 'o'. Inglis frowned at her uncomprehendingly for a second, then wheeled around, his own jaw falling. "What the devil –?"

The vampire gave him a hard smile, and nodded cordially to Cecily. "I know, I know. I'm s'posed to be lying low." He hefted the railway spike in his hand and examined it appreciatively. Looked Inglis in the eye to see if he remembered. The man stared at him with flared nostrils and a constricted look. "Couldn't help myself," the vampire said, parodying a rueful shrug. "Had to strike while the irony's hot."

The sound almost made Arthur choke. A scream that rapidly lost its humanity and turned into a sick gurgle before tailing off. Everything inside Arthur became cold and liquid and it was seconds before his brain reconnected with the rest of him. He had never given any thought to whether he was a hero, but he found himself surging forward into the street before his cowardice – self-preservation instinct, he'd later think – had a chance to stop him. He reached Inglis's carriage at the same instant as the murderer, only its shaking bulk separating them, and only the stranger's preoccupation keeping Arthur from his sight. The horses, terrified by the scream, tugged frantically at their traces, and the panic-stricken driver had raised his whip. As Arthur watched, crouched behind the insubstantial cover of the wheel hub, the coachman brought it crashing down as the stranger – who wasn't a stranger at all – raised his arm. The leather lashed down and wrapped around his wrist and forearm with a stinging crack, but the stranger didn't flinch. Instead he pulled back, the lash still binding his limb, dragging the driver toward him. For an instant the driver clung on, paralysed, then he let go the whip's handle. The stranger staggered back from the loss of tension and the horses bolted, dragging the carriage behind them, the driver clutching desperately at his bouncing seat.

The stranger watched them go with something that looked briefly like disappointment, then turned back to Cecily. Arthur had screwed his eyes shut as the carriage left, dissolving his hiding place, but when he opened them the assailant had his back to him. Arthur tried to remember to breathe.

"You're – not human –" Cecily's face was porcelain white, her eyes as round as her mouth. Her voice was strangely low.

"Not very," allowed the creature in William's body. They stared at each other over the grotesque corpse sprawled on the path.

"Aren't you going to scream and faint?" he asked.

Cecily held his gaze, then extended a faintly trembling white hand and cupped the side of the face that no longer looked anything like William's. She stroked the pale skin with infinite gentleness, reaching up to the distorted brow. His face melted back to its human shape instantly and he stared at her with astonished eyes, blue again. Cecily's face was soft now too. She tilted her head, and the young man copied the gesture unconsciously. "Cecily," he breathed, so overwhelmed that the word caught in his throat.

"When?" she asked. His eyes shone desperately. She ran her forefinger back and forth gently on his cheek, and William inhaled very audibly, seeming to fight to keep his eyes from falling closed.

"Two weeks ago. The night I saw you last."

Cecily's eyes widened again. Slowly, she leant in and pressed a soft kiss onto his cold, parted lips. "I'm sorry, William."

He straightened up and drew away from her, narrowing his eyes. "It's not William any more." He gestured vaguely toward the body without looking down, indicating the spike planted in the centre of the brow.

She withdrew her hand and nodded, not breaking his gaze. "Spike. It suits you," she murmured. After a brief smile, he looked down uneasily, as though searching unsuccessfully for words.

"I wish I'd –"

"Don't wish," said Cecily hurriedly. The man she'd scarcely known as William frowned. "Go out by yourself and make things different."

He smiled at her quizzically, then nodded decisively. "I'll see you around," he told her, firmly. He tilted his head back briefly, as though trying to keep from laughing, and took in the thick night sky. Then, without looking back at Cecily, he turned and left, disappearing back into the shadowed streets that led off the square.

The silence when he was gone was sharp as a held-in breath, the streetlamps' glow obscene over the horribly colourful tableau. Arthur found himself staring directly at Cecily. The other man had left without paying him the slightest bit of notice. Calmly, with great composure, Arthur fainted.