A re-imagining of the Great Detective and his partner as Charlotte Holmes, a traumatised woman, and her companion Dr Watan, an Indian doctor, as they investigate nefarious activities and a conspiracy to bring down the British Empire at the dawn of the 20th century. Charlotte, a brilliant yet erratic polymath, is escaping from an enforced confinement whilst being pursued relentlessly by her husband when she encounters Dr Watan on board the Calcutta Tiger Express. Our heroes investigate a murder on the train and learn the intended victim was the young Maharani on her way to meet her new husband, the Maharaja of Ratnam Nagar. They journey to the Kingdom and uncover a power-struggle with the all-powerful matriarch Mataji and her evil cult of Thuggee killers. Devious plots are hatched, ancient rituals revived and evil machinations unleashed to secure the prized Ruby Throne; but will our heroes survive to reach Calcutta to unveil the conspiracy? The Viceroy's Christmas ball becomes the focus of the conspiracy as all the principle actors converge for a final showdown that will decide the fate of the British Raj. A tale of sorrows unmourned, love unrequited, killers unmasked and ambition unfulfilled.