It was not the first time I had done business with O'Carroll, though it had been nigh on three years since I had seen the man in these exact same circumstances. I grunted in reply, not wishing to admit to him any more than he already supposed.

He made comment on how much more refined I looked now compared to when I had frequented his shop in days past, in awe of how I'd turned my life around, though quite perplexed by how I had done it. He asked me about the scar on my face running from nose to lip and, when I offered him no reply, he scoffed, nodded and said: "I see you are still chasing that foolish hobby of yours. You'll never change, Joseph."

I had no love for his small talk or boorish observations, and beckoned him with a gloved forefinger. He complied and produced a stained, unlabelled brown bottle from beneath his counter; the sight of which bred a familiar, obnoxious prickling on the roof of my throat.

"Twenty drops should see you through the night," said he as he handed me a small vial of liquid of a rich, chestnut hue.

I produced a second penny. "Make it fifty."

The loose skin on his bristly neck swayed as he shook his head, though I would sooner he left me dry than surrender my request. "Something tells me that the absent lustre in your eyes is no mere symptom of insomnia. Your nightmares must be truly insufferable."

Growing impatient, I tipped the liquid onto my tongue, caught on the verge of retching from the bitterness of it. It was a taste from my youth I had grown accustomed to, but now, after several dozen months of abstinence, I was most surprised I could stomach the vile tincture at all.

"Nightmares, O'Carroll? You have no idea," I told him, and slammed the vial on the counter in disgust at myself.

I dared not step foot in Tom Rawlings' home under the influence of opiates, however mild. The man was adamant that he would not tolerate or excuse the misuse of narcotics in his household – he was, in fact, one of the few people I knew of who also detested cigarettes, complaining that the smell of tobacco upset his digestion. Although ... from conversations with his wife, Ida, I had come to understand that my landlord had not been quite so above it all when first they met.

Alone in an alley off Clement Street proper I huddled against the brick aspect of an estate agent's, curling the nicks of a weather-beaten poster of some greatly inflated concert cellist whose name I did not remember. It may have been but the tincture's spell asserting its influence, but true enough at the time, I might have sworn the young man in the poster was laughing down at me; his unseeing eyes according me a snide frown.

Notwithstanding, I let the drug welcome me into its airy embrace, releasing me from the sobriety of a gentleman's life and teasing forth the grin of a fool, though by which variety of amusement I would never know. It began with a queer sensation in the imaginary space between my eyes and the front of my brain, as if the waves of some blissful Far Eastern ocean bay swept out my thoughts like fine silt. I lolled my head against the poster, smiling for the heady euphoria that took me back to being an adolescent falling in love for the first time.

Make no mistake. I am certainly not well pleased with myself.

After reconnecting with my dark and foggy surroundings, I stayed my condition, and bargained that I could arrive at Corgaine's lab by the toll of six. With my better judgement clouded – and similarly, my inhibitions – I discovered within myself the spur to tell Frederic of what I had witnessed the night of Nina's birthday. I had been formerly much too distraught, so entangled in my own, pathetic suffering of the mind to have worried much for my accomplice's. I had already failed one person, and now that person lay cold in countless fragments. Never again would she resemble the newly wed Mrs Viola Howard and it was, in part, my fault.

By God. If the same fate befell Frederic ... I did not think it possible my melancholy could drag me further by any appropriately proportionate amount. That is to say I valued the boy far too much to even think of how I would cope if he too should meet with gory disaster. Since the fateful collapse of my rapport with Corgaine, I had not let myself befriend many. But now, steered under the authority of Cecil's particularly potent tincture, I finally listened to endearment.

When at last I stumbled through the cemetery and arrived at the lab, it was Corgaine who answered my knocking. He took one look at me slumped against the doorframe and, though I was quite certain the man would return the door at once, he seized me beneath the underarms and manipulated me inside towards a stool. Like some weakly patient he lowered me to it and sat nearby without need of any comment. He did not jest, nor did he complain. He did not say or do much of anything, in fact, only now and again lifting my chin from my chest to ensure I was still conscious.

Understandably, and by virtue of my own foolishness, I do not remember much of that particular visit. I cannot describe in detail the exact nature of the fleshy horror I saw from the corner of my bleary eyes upon the surgical table either, only that there it existed in full view, red, grey and raw. I recall the putrid, pickled stench of the thing mingled with whatever manner of balmy compounds he had preserved it in, but the full significance of this mutilated atrocity did not reach me through my intoxication. The despicable bastard need only look at me to know that his secret would stay safe. And yet I curse myself until this day, for had I been fully composed I would have seen everything I'd needed to expose him for what he was.

From what I do remember, the body was not whole.

"Frederic is not here," he told me after what felt like a painfully prolonged silence. I swayed upon the stool, vaguely aware that I was doing so, yet still without the urge to stop myself. "I'm afraid the boy has taken ill. I have not seen him since yesterday."

I lifted my head to gauge his demeanour. Corgaine half sat atop his work counter with his arms folded across his chest betraying his usual, petulant manner. I was convinced I spied a smirk set about his lips however, although when my gaze refocused I saw that he was, in fact, not by the slightest dab amused. Still, as he so often did, he exuded smugness that only served in me despising him all the more sorely. Had I spent another penny with O'Carroll, perhaps my inhibitions might even have excused chiding him for it. But I refrained – something I found demanded exponentially more discipline as the month had passed.

"What did you do to him?" I asked. My words spilled as if my mouth were packed with dirt. Corgaine reached down and wiped away the dampness in the corner of my lips. If truth be told, I wished for him to linger there a moment longer, but banished the very notion of it at once and batted him away. "I need to see Frederic ... to warn him ... about ..."

"You are pathetic," Corgaine snarled. His change in attitude came needle sharp, as though he addressed a second, unseen guest behind me that I had missed in passing, or that there exists a stark gap in my memory, which is all the more plausible. "Look at you," he continued. "Here. Babbling as if you are some half mad lowlife on the street. What has become of you, Frans? This is not the man you are."

I knew not to whom he spoke. "Frederic," I tried again. "Not Frans. I need you to tell him ... the vicche ... I ..."

"We've been through this." He lurched to his knees and gripped my shoulders with such force my head rolled back on my neck, tossing my hair into my eyes. With a gentle forefinger he swept the damp strands clear of my face. "You ... You are alone," he said, enunciating each word. There was a kind of sad desperation set in his gaze, as if ... No. Corgaine had a heart once, but he had long sacrificed it. "You are the exception. You are the unexplainable you seek. And your endeavours ... Joseph, you will not find others like you."

The rest, to my utter disgrace, and no matter how strenuously I concentrate on that psychotic moment, does not come to me. It was a feeling familiar to a strange dream from which I had awoken, only able to revive the merest essence of it; the feelings and emotions that lingered whenever I could bear to revisit. The weirdness of it was oddly perceptible, which stood as a testimony that I was, for the majority, aware of my immediate environment ... Though exactly what lay in pieces upon Corgaine's surgical table also remained forever beyond the realm of even the most intensive recall.

There also existed some things about that night that I knew with unsung clarity, but without being aware of how I came to know them. I can only presume it was Corgaine who told me that Frederic was keeping well at home while he recovered from a seasonal cold, of which he insisted was not a suitable ailment to import into a sterile, laboratory environment.

I also knew that I arrived back to my attic room in the Rawlings' household whole and safe, with my landlord no wiser to my impulsive trip to the chemist's and my subsequent inebriation. I assume that it was Corgaine who took pity enough on me, though how much of a role he played in escorting me to the refuge of my tired old mattress, I never did care to ask him.

Of one final thing I can barely summon the conviction to write. It is this – if indeed Corgaine was the only person I stumbled across that night – that drives a spear of lead through my heart whenever I think of how it was completely preventable. If I had done the right thing that evening, and instead retired to my room and locked the door where the increasingly intrusive housemaid could not come within reach of me, and had I not so carelessly and senselessly turned once again to opiates to detach myself from my woes, my cause for alarm could not have possibly have occurred.

For once I was free of my initial stupor, it was then that I knew I was not alone in the attic. By my side, with her body bare and pallid, and her curly blonde hair spread loose over my pillow, lay the housemaid.

Her blue, china-doll eyes were already opened when I realised the full magnitude of the deed that I had done. But whatever she herself thought or felt about the way in which we woke up naked and entangled, she never did express.

For she was already hours dead.