Found floating in the Straits of Bosporus, Constantinople, is the body of a woman, Euphemia Bray, alleged Theosophist and wealthy friend of Madame Blavatsky, a controversial Victorian mystic. Thus begins a British mystery and an investigation by Church and Queen to discover whether Blavatsky is a true mystic or an imposter, an adventure which moves from England to India.

Helena Petrovna Blavatsky was a real person, known as 'the most remarkable woman of the century' and the 'yogini of the West'.

Cambridge Professor of Divinity Paul Hartley and graduate student Giles Bluecastle face a host of dangers, inquiring into Bray's death and the authenticity of Blavatsky's reported occult powers. They visit sacred sites and institutions to interview clergy, savants, monks, yogis, and kabbalists on their sojourn to India via Ireland, Greece, and the Turkish Ottoman Empire.

Interwoven within the adventure are the machinations of British and Church rule, conflicts between authority and religion, and debates over the realities of mystical experience.