Set amid the clip and clatter of hansom cabs and the popping of the gaslights, this intriguing mystery introduces Dr. James Mortimer, the man who brought the case of the Hound of the Baskervilles to the attention of Sherlock Holmes. Here, Dr. Mortimer tells a tale of how he came across his second and most challenging case ever.

In 1890, the young Dr. Mortimer is numb with grief over the death of his wife and decides to close his own practice and begin a new life for himself. He winds up in London and is asked to fill in for another doctor with an emergency. Dr. Mortimer agrees and his last call of the day brings him to an address in Aldgate where he meets the captivating Lavinia Nancarrow. Intrigued and worried by the overbearing solicitude of the girl's guardian who keeps her a virtual prisoner, Mortimer determines to discover the reasons behind Lavinia's confinement.

Engagingly absent-minded but incessantly curious and observant, Mortimer is aided in his effort by his formidable consort, the liberated Dr. Violet Branscombe. Together they unravel a mystery as dark and sinister as the East End Alleys of Victorian London.

A retired Calcutta merchant with a guilty secret, a decadent fin-de-siecle artist who frequents an anarchist café in Whitechapel and a seemingly impossible murder are the key pieces in the puzzle, which Mortimer soon finds himself trying to solve, in Gerard Williams's Dr. Mortimer and the Aldgate Mystery.