Autumn in London is usually the most genial of seasons, but in the year 1881, atypical cold and damp weather arrived early and winter's chill could be felt towards the end of October. It was on such a night that Mr Sherlock Holmes, the up-and-coming amateur detective, chose once again to demonstrate his analytical methods to his flatmate, Dr John Watson, an invalided veteran from the recent Afghan campaigns.

For some time it had been the detective's intent to rekindle Watson's early fascination in his cases. For the doctor's own part, his burgeoning interest was all but doused when his inconsistent health precluded his participation in active investigations. Much against his will, he had been relegated to the position of bystander, and this left him deeply disheartened.

Indeed, the year had been one of frustration for the two gentlemen residing at 221B Baker Street. In July, Watson had failed to convince the Army Medical Board of his suitability to resume his commission. His health had not sufficiently mended by the time of his review, nor was it reasonable to expect it would do so in the future. Holmes had hoped that the repatriation of the doctor's old regiment would lift his spirits, when in fact, the opposite turned out to be the case.

As it turned out, Holmes had neither the inclination nor the time to dwell on his friend's difficulties when his own fortunes took a downturn. He had taken an interest in a sordid affair which monopolised his energies and talents for most of the summer, concluding with the untimely death of his client and no payment for all his efforts. Only after two months of miserly existence and accepting cases out of necessity rather than interest, was he again confident in his financial situation.

On this particular night, Holmes had contracted the services of Sid and Barney, and their carriage for hire. (The former being the driver, the latter, the horse.) Earlier in his career, Holmes had helped Sid out of a delicate situation and Sid, in gratitude, placed his services at Holmes' disposal. The carriage was a compact variety of two-axled growler. Strictly speaking, it was more vehicle than Holmes required, but the four-wheeler provided a smoother ride than any hansom and it was completely enclosed against the elements; both were important concerns on a night like this which threatened rain at any moment.

Whitechapel was one of London's poorest districts. Destitution and desperation combined to make it a dangerous place, especially after dark. Each morning brought news of some crime being committed in the backstreets and alleyways. Violence was a way of life for poor who were accustomed to the bleakness of their surroundings. It was precisely for that reason that Holmes dragged Watson out of their comfort of their Baker Street flat late that night. He was hoping for a chance to demonstrate his deductive methods, and he was certain he would find such an opportunity here.

Midnight found the carriage easing its way east along Whitechapel High Street, when Sid drew it to a halt. Holmes opened the door to see why they had stopped.

'Doctor, Sid has found something promising. Follow me!'

Holmes led Watson to where a Police maria was stationed. A hard-faced constable stood by the horses.

'It's Inspector Gregson's luck of the draw tonight, Mr Holmes. Someone reported a stiff in the mews. It's a right warren back there. You can enter through yon gate but you'll need your lantern. Watch yourselves in them alleys. The local citizens are just as like to drop a rock or a brick on a fellow's head just for sport. I'll not be moving far from the streetlamps of High Street if I can help it.'

The constable had been correct. Negotiating the labyrinthine path without a lantern would have been impossible. The stench of squalor was particularly strong. Watson did not want to stop for a closer look at what the rats were eating. The narrow alley opened onto the mews. A light fog further reduced the illumination from meagre gas lamp situated on the back of one of the establishments. In the distance, two other globes of diminished light could be seen as well. Under the second faint pool of light, cast by lamp behind The Stag, a small crowd had gathered. Holmes led Watson closer. A man's body lay amongst the rubbish, his identity concealed by the bloodied cloth covering the remains of his head.

Inspector Gregson is investigating a brutal murder.

'Well, Doctor,' Holmes smiled. 'This should prove to be most instructive.'