EDIT: SORRY FOR NOT UPDATING IN MONTHS; MY FIRST BOOK IS RELEASED!
Hopefully, I can devote more time to this fic now b/c I missed it terribly ^^;
P.S. There are illustrations to go with each chapter on ao3. It makes the clues more interactive and gives a nice flavor to the story. Fanfic doesn't let you include images so you can read the full detailed story on here: /works/6246226/chapters/14310889, or google "Book of Cipher by ThatMysteryWriter"

Ch 1: The Game is Afoot

{Cielle's POV}

I imagine decent, upstanding aristocrats hailing from nobility circles would seldom find themselves in such compromising states—bent over and down on their knees, crawling among the shadows like some marauder. But I, being the Queen's guard dog, welcomed these singular predicaments.

Shifting my eye-patch under the counter, I held up the anonymous telegram wired to Scotland Yard, the cryptic words lit by a sliver of moonlight.

'NRWMRTSG YFITOZIB. QVDVO SLFHV. GLDVI LU OLMWLM'

Given the Yard's usual state of incompetence, it hardly came as a surprise those bunglers had failed to decipher so simple a message. It wasn't particularly difficult to see the words formed a simple substitution cipher of reversed alphabets: A's replaced Z's, B's replaced Y's, C's with X's, and so forth. The decoded message bluntly stated:

'MIDNIGHT BURGLARY. JEWEL HOUSE. TOWER OF LONDON'

A small part of the Tower of London, the Jewel House where the Queen housed the Crown Jewels. Though the warning telegram had been wired to Scotland Yard, as Queen's loyal guard dog, this task fell in my jurisdiction. Tonight I'd catch the swindling culprit who'd dare trifle with Her Majesty—and consequently me.

The showroom clock began striking the hour. I stuffed the slip into my frock-coat and flattened myself against the woodwork. My pulse sped up with each chime. After the twelfth sounded, a heavy silence hovered in the air. I waited and waited, the seconds passing by at a glacial pace. Then I heard it. A tight knot formed in my chest as the windowsill's rusted hinges screeched in the darkness. Given the undersized windows of the showroom, I suppose it was small comfort to know some rat-like man had just clambered in instead of a beast.

Light scuffs on the floorboards proceeded without an inkling of hesitation. The rogue flitted past Her Majesty's royal regalia, past the sceptres, imperial state crowns, and other priceless items that stood hundreds of years of monarchy.

Then he stopped, as if he finally found what he came here for. A hand over my revolver, I rose slightly from my hiding place and blinked. The silhouette in front of me hardly belonged to a man at all but rather a woman—that too, one I recognized.

Irene Diaz . . . ?

The opera singer I had invited to a banquet along with Mr. Wordsmith. What the deuce was she doing here?

I narrowed my vision. With her back to me, Irene hovered over a nearby counter, her long, blonde hair spilling over a glass display. Through her curtained hair, I caught her hand fishing a delicate artifact out of its confines.

The Queen's diadem.

"I'd advise you to stop right there, Miss Diaz." I kept my voice soft as I sprang from the counter. "If you don't, I'm afraid you'll be in for quite a vamp."

At the sound of my voice, the woman tilted her head in a cataleptic manner. Like a mesmerized puppet, her dull, glassy eyes locked with mine, and a vacant smile crept her lips. A chill crawled over me. "What the deuce you think you're doing?"

And just like that, she completely dismissed my words and returned to her plundering. I stared at her in disbelief until a series of barks emerged in the distance. The Scotland Yard terriers. The moment I heard the barks, so did she. The woman's queer expression began to morph before me. Her face convulsed; her clouded eyes turned hard.

"A . . .dog?" Irene whispered to herself. She whirled to her side, and her face blanched at my sight. "I-it's you . . . " Her trembling hands dropped the diadem with a clatter. She slowly backed away from me, her lavender irises wildly darted around the showroom—until they landed on the half-opened window.

"Don't be foolish," I whispered.

The opera singer didn't heed my words. Like a frightened deer, she bolted, her long dress swishing with every step. Just as her fingertips reached for the windowsill, I extended my foot, causing her to lose her footing and stagger backwards. Seizing my chance, I grasped the train of her dress and brought her to the floor.

At that very moment, the two Scotland Yard officials who had stood watch outside the entrance burst through the doorway. Lord Randall Delacourt, Commissioner of Scotland Yard, swooped down on her like a hawk after a rabbit. She released a cry as Inspector Abberline seized her wrists and cuffed her. Once she was detained, the Commissioner wheeled around to face me, his voice sharp as glass. "What in blazes do you think you are doing here?"

My gaze drifted at the restive terriers that circled him before I pointedly caught his eye. "I merely came to tidy up after the lumbering dogs, Commissioner."

Delacourt's jaw clenched. "You were meant to find the Yard a lead, not blooming follow it."

"Au contraire," I replied with a demure smile. "While it is true that trivial cases like burglary fall in the Yard's jurisdiction, given that theft was attempted in the Queen's Jewel House, this falls completely in my vicinity, wouldn't you say? I daresay, it is you who is infringing here."

Delacourt pursed his mouth to retort when Irene let out a strangled plea. "U-unhand me. I'm innocent, I tell you."

"If we had a shilling for every time we heard that," Abberline scoffed.

"But, it's true, I swear to you it is the truth!"

"Then exactly why are you here, miss?"

"I don't know. I-I must have been sleepwalking." As soon as the words left her mouth, Irene stared at her mid-calve heels and her bustle gown. Her cheeks deepened in color, matching the pink silken fabric of her attire. I casted her a disbelieving look. Surely the woman could concoct a better story than that. If she was prepared to lie, she could, at the very least, make it a convincing one.

"In day wear?" Abberline's question dripped with the sarcasm. "State your name, miss."

The opera singer's lips trembled. "Irene Diaz."

The Inspector reached for his notebook. "And how did you happen to bypass the main entrance's security measure?"

"I . . . don't know," Irene whispered. She gazed at her quivering hands.

"She entered through there." I pointed to the window in question. Irene stared at it with worrisome eyes as I strode past her. December air seeped through the crevice, submerging the room in coldness that made my breath materialize. As I tried to shut out the irksome draft, something moved in the shadows. I jolted, my hands still gripping the windowsill. That blasted-

"Something the matter, Lady Phantomhive?" The commissioner's eyes narrowed at me.

"It's nothing." I murmured. "Just some slipshod bat . . ."

Slowly, I returned my attention to Abberline who was wrapping up with his unsuccessful line of questioning. His eyes flickered to the diadem lying on the floor. "And now perhaps you'd care to explain the most important bit of all. Why did you attempt to steal Her Majesty's diadem in the first place, Miss Diaz?"

Irene bit her rose stained lip though her eyes shone bright with resolve. "I told you. I didn't steal it. I don't know anything about the—"

"Enough of this claptrap, Abberline." Commissioner Delacourt stared at his watch with palpable irritation. "It's past decent hours, and I have to be up at Imperial Academy in the morning. Proceed with the arrest. We shall resume her questioning when she is feeling more cooperative." Irene blanched.

"Yes, sir."

The Commissioner grabbed the terrier's leashes as Abberline towed Irene outside. Curtains of black clouds unveiled a quarter moon, the silvery light falling upon us. I trailed the group from a measurable distance, my eyes searching the dimly lit alley. Where the devil was he? And then the two terriers that flanked our party broke my thought. They gave a little growl, their leashes pulling taut.

"Well, don't just stand there, you dolt—check it," the Commissioner ordered. "I'll keep an eye on this one."

Abberline grunted his assent as the terriers broke free, their feet thundering all the way to the back of the London Tower. I followed behind him. A chorus of moans intermingled with the barks. The hairs on my arm stood up. I hastened behind Abberlines's trail until he came to an abrupt stop. In front of us sat three men, bound and gagged, their faces etched with horror.

Recognition filled Abberline's eyes. "Hold on just a moment, you lot are-"

"The French smugglers the Yard failed to arrest last month," I said—emphasis on failed.

The men made muffled sounds through their gag. I removed one of them when the burliest man lunged at me. I careened out of the way, leaving him to cling to the Inspector's collar through his chain-bound hands. "Il avait un visage de bête comme!"

"Pull yourself together man!" Abberline yanked his uniform free.

The mustached man next to him whimpered. "L-lesus naturae . . . m-monstre . . . Je l'ai vu un f-f-antôme avec un visage blanc."

"Beg your pardon?" the Inspector asked.

"A phantom." I narrowed my eyes into the dank, shadowy alley. "They say a white-faced phantom attacked them."

"Z-ze girl es right," the smallest of them said in a thick French accent. "It vas h-horrible."

With a small sarcastic-laugh, Abberline replaced the thin chain around their wrists with handcuffs. "What utter poppycock."

Commissioner Delacourt led a stricken Irene Diaz to the scene. "Heard all the commotion. Do you not have this under con—" He stuttered at the sight of the band of cowering smugglers. "Are they who I think they are?"

"Ay," said Abberline. "I expect they were in cahoots with this young lady here, attempting to steal the diadem in another one of their smuggling operations."

"Is that so?" Delacourt eyed the men coldly. "How unfortunate their rendezvous ends here." He shot Irene a disapproving look. "For all of them."

"I swear I don't know any of them," she cried. "You have to believe me! I beg of you." When she found no sympathy from the officials, she turned to me in desperation. "Please, you can vouch for me! Grimsby and I were guests at a banquet you held last year at Phantomhive manor."

"Hold on a minute." Abberline stared at her hard. "Now that you mention it, I do recall something about that event. A few officials from the Yard were dispatched to Phantomhive estate to collect Georg Von Siemen who had been sacked most mysteriously. To date, the Yard never figured out who was responsible for that unfortunate event. If I'm not mistaken, I believe you were present when this all took place, Miss Diaz." The opera singer recoiled as though she'd been drenched with a glass of wine again.

"What are you insinuating?" she whispered.

I raised a hand to prevent this drivel from going further. "Are you lot really that thick-headed, or is this the typical manner you conduct your investigations?"

"Lady Phantomhive," Delacourt began in frosty accents, "while we are obliged to your small assistance with the earlier telegram, I must ask you to stop with this insufferable interference, and leave the rest in our capable hands."

I balled my fist up. Insufferable interference?

Abberline sighed. "Seeing as it is rather late, do you need someone to accompany you back to Phantomhive manor?"

I spoke through grit teeth. "I am exceedingly grateful for your offer, Inspector, but my butler shall see to it instead. I left him near the corner."

"Very, well," Abberline said. "In that case, we'll take our leave."

"Please do."

I watched the little party fade in the distance. Irene Diaz stared at her cuffs, her face crestfallen and perturbed. Only when they reached the corner did she chance looking over her shoulder. She held my gaze in desperation; her lips beseeched me, mouthing words so clear and unmistakable.

Help me.

I frowned as I returned to the showroom. Something about this simple theft was off. Pressing my fingers against the glass display, I committed the diadem to memory. Framed in silver, it was elegantly inlaid with twelve tiny gemstones: diamond, sapphire, emerald, moonstone, amethyst, aquamarine, garnet, sardonyx, ruby, topaz, opal, and zircon. Expensive though it was, it certainly wasn't the priciest item in the Jewel House, and Irene Diaz certainly wasn't in any need of coin. The woman after all came from High Society and probably possessed countless of pricey trinkets herself. She had no real need to engage in this petty theft.

Then, why did she engage?

I paused, my theorizing interrupted by a silhouette that crept fluidly across the wall. Its shadow loomed behind me, growing larger on the floor until it finally engulfed my own shadow.

I smiled to myself. "Well, you sure took your time."

"My apologies for the delay, young mistress." Sebastian eased in from the shadows, his sculpted features and obsidian hair spotlit by the moonlight. He dusted off his satin gloves. "I fear I had gotten a bit caught up eliminating the rats scurrying about. I trust I haven't missed anything of importance?"

"Not particularly. But if you must know, I caught the swindler."

"Is that so? In that case, permit me to commend you. It is refreshing to see the young mistress being self-sufficient." His graceful tone hardly veiled his impertinent tongue.

I gave him a biting stare. "The plunderer turned out to be Irene Diaz."

"The opera singer from Lyceum Theatre?" Sebastian lifted a brow. "That is a touch curious."

"Yes, curious. Though not as much as the scene that followed." I looked him straight in the eye. "Three men, bound with restraints, bumbling like a pack of imbeciles about some horrid monster that came upon them."

"A monster you say?" A frown marred his elegant visage. "My, that sounds rather frightful."

"Quite so. In any case . . . " I held up the long, thin chain that had bound the men and deposited it in Sebastian's gloved hand. "I believe this belongs to you."

Sebastian chuckled as he reattached the chain to his pocket watch. "Much obliged, young mistress."

My lips curved. "Come, Sebastian. Let us return to the manor. I've had enough of staying awake at this ungodly hour—"

A deafening crash rippled through the air. I wheeled around. Panic frosted my skin. A blizzard of glass shards hurtled in midair, heading straight for me. Before I could think to shield my eyes, a band of steel encircled my waist. I grasped a fistful of a fabric as the glass showered down, its discordant tinkling filling my ears. When it finally tapered to silence, only the sound of my shallow breathing remained.

Wisps of silky, black hair brushed against me. I snapped open my eyes, and my breath caught. Sebastian's face hovered above mine, his demonic eyes blazing as they bore into my own.

"What . . . the dickens just happened?"

"It would appear someone has broken the showroom windows, young mistress."

"Thank you for your scintillating input," I snapped.

"Pardon my simple answer for a simple question. In any case . . ." He paused, his gaze traveling across my face, then lower. "Are you quite unhurt?"

I might have been alright, but the weight on top of me was considerable. Little by little, I became aware of the hard form pressed against mine and to my mortification—my vise-like grip on his uniform. My shaking hands clung to his white shirt so fiercely that one of the digits had slipped into a fold between two buttons. I uncurled my fingers from the lapels of his suit at once.

"A bit flattened," I said quietly.

"My deepest apologies. It slipped my mind how delicate the young mistress is." I eyed him tetchily as he rose to his full height and inspected his tattered uniform with a sigh. "Remarkable how my attire never seems to stay intact when I am in your presence for too long."

"Surely, your clothes are used to such trifles by now." I curled my lip in distaste as he helped me to my feet. Carefully to avoid the glass shards, I flitted past him to the broken window. As I inspected the windowsill, something fluttering on the floor caught my attention: a flower petal? Cerulean blue, velvety, and of a spring variety too rare to find during the coldest month of the year. Immediately, I pocketed it.

"Peculiar," came a murmur. I spun around. Sebastian knelt on the littered floor, his eyes gleaming as he freed a scrap of paper underneath a glass shard.

"And what may I ask is so peculiar?"

"Perhaps you ought to see for yourself, young mistress."

He held out the scrap, and my gaze swiveled at the handwritten words in deep blue ink. "That's . . . my name." I stared hard at the spot that read 'Cielle Phantomhive.'

"Indeed," whispered Sebastian. "But that is hardly what makes it curious."

When I turned over the scrap, I understood why.

'Dec 12th

1325 205125718113. 791812 9141415351420. 2085 71135 919 16151520

25152118 522518 231203862112 61895144,

- 7891011 12'

Another blasted cipher.

I scanned the first string of numbers: 1325. If the numbers corresponded to the alphabet, 1 = A, 3 = C, 2 = B, and 5 = E. But that hardly made any sense, unless 'acbe' was a word in the English dictionary. I considered it again. Perhaps the cipher consisted of double digits as well. If 13 referred to 'M', and '25' referred for 'Y'. . .

My.

"Sebastian, a quill," I ordered.

Sebastian promptly retrieved one and deposited into my unsteady hand. I began marking up the paper like a tempest, decoding word after word. In minutes, I had unraveled the entire message, save the last line. My fingers dented the paper.

"Well?" intoned Sebastian.

"She was telling the truth," I whispered darkly. "Someone is playing me, Sebastian. Look for yourself."

Sebastian leaned in close, his fuchsia orbs flickering as he read aloud the text:

'Dec 12th

My telegram. Irene innocent. The game is afoot Phantomhive.

Your ever watchful friend,

-7891011 12'

Author's Note: The Ciel I chose to depict is probably closer to Shiori from the live action of Kuroshitsuji. Upcoming chapters are written from both fem Ciel/Sebastian's POV. I tend to prefer SebaCiel fanfics with a complex, interactive mystery (Basically what KuroS is at its core-right? ;D ) with a romantic subplot. So yup, that's where this fanfic is headed.

Anywho, let me know what you guys think so far : )

EDIT 7/21/18: Apologies for the hiatus! MY SECRET WRITING PROJECT IS NO LONGER SECRET! My first book, "Alice in Winterland: A Fangirl Novel", is out on kindle! ^o^ It's a story for fangirls about fangirls by fangirls. We wanted to create a book that can make you smile on a rainy day. A book that celebrated fangirling in all its glory and all those feels. If any of the following catches your attention—manga illustrations, cosplay conventions, the woes and highs of fanfiction writers, shippy fanart, nerdy puns and pick up lines, riddles, Tumblr-ing, and references to fandoms like HP, Sherlock, Sailor Moon, YOI, Kuroshitsuji (how could I not) —you can read the first chapter on Amazon. Just search "Alice in Winterland: A Fangirl Novel"

I hope you fall in love with this story as much as we have. ^^

Happy fandoming! xoxo