The Vital Principle
In 1815, Mr. Knighton Gaunt is asked by Lord Crowley to attend a séance and reveal the spiritualist as a fraud. But the séance ends abruptly and Lord Crowley is poisoned during the turmoil by an unseen killer.
Gaunt is left to investigate not only fraud, but murder. Suspicion turns to the spiritualist, Prudence Barnard, but as Gaunt digs deeper, he finds motives aplenty among the guests.