A narrator describes a séance in which a medium types out a manuscript chronicling a man’s involvement with experimental procedures that alter or replace bodies. The framed narrative traces a sequence of uncanny scientific interventions, moral and philosophical reflections, episodes of hallucination and violence, and the creation of hybrid or monstrous results. The book moves through investigative and interpersonal interludes as consequences escalate, culminating in the death of the principal experimenter and a troubling aftermath that examines identity, bodily integrity, and the costs of scientific audacity.