Louis D’Ascoyne Mazzini, the son of a disinherited aristocratic woman and an Italian opera singer, seeks revenge for his mother's mistreatment and aims to claim the dukedom of the wealthy D'Ascoyne family. Socially snubbed by his aristocratic relations, Louis schemes to ascend the family hierarchy by systematically eliminating the eight D'Ascoyne family members who stand between him and the dukedom. With meticulous planning and a cold, calculating nature, Louis ingeniously dispatches each of his distant relatives, adopting various clever methods to mask his lethal intent. Concurrently, he maintains relationships with two women: Edith, the widow of one of his victims, and Sibella, a childhood acquaintance married to another man.

As Louis progresses in his quest for vengeance and power, he becomes increasingly confident in his abilities and unscrupulous in his methods. The simultaneous management of his romantic entanglements with Edith and Sibella adds layers of complexity to his grand scheme. Despite the façade of gentlemanly decorum, Louis's ruthless ambition and keen intellect drive his singular focus on the ultimate prize. As events unfold, fate plays an unexpected hand, bringing Louis's meticulously laid plans into question, culminating in a dramatic turn of consequences.