The fire was almost down to its embers by the time I'd finished reading. The comfort of our rooms did nothing to efface the startling impression left upon me by Holmes's narrative.

I passed my hand over my brow. "My head's in a whirl," I remarked, barely able to voice my feelings.

My friend rubbed his hands together, an intense expression settling upon his hawk-like features. "I confess that for some time," he said "that sickening trade became an idée fixe with me. I would scour the papers for news of missing girls, for clues that might bring the whole monstrous business tumbling down upon their heads.

"I discovered that it was a simple thing to find the proofs. Almost impossible to stop the trade. For these people have agents in all walks of life. They are cunning, without remorse. There are no subterfuges too artful for them. Women and girls - often poor, young, and alone - are easy pickings. They are the prey in a world of wolves."

1868: Cambridge. A young Sherlock Holmes accompanies his brother, Mycroft, to Cambridge, to investigate a curious death, in a case which will prove formative for both brothers.

1893: London. Doctor Watson, still mourning the apparent death of his friend, is invited by Inspector Lestrade to consult on a gruesome murder, which has all the hallmarks of the Ripper.

Two cases. Four investigators.

A locked-room mystery. A trunk murder. Missing girls. And a conspiracy involving the highest echelons of Victorian society. All linked by one, bloody thread ...