The narrator, the author’s alter ego, who leaves his wife and child to pursue knowledge of chemistry and alchemy. His scientific experiments leave him incapacitated, his hands bleeding. He enters a hospital, where he is surrounded by decay, disease, and death. A brilliant and high-principled man, he is tormented in his soul and body by a number of hidden and diabolical assailants. He sees himself attacked by worldly enemies and, increasingly, otherworldly ones, demons and satanic forces. His soul writhes in fear of shadowy assailants, planning unknown mischief against him. He is disgusted by the stenches, horrid noises, and rude, base people that beset him, and he is in torment as electrical emanations, foul air, and other poisons destroy his health and worry his sanity. He offers this narrative as an account of his trip through nothing less than a literal hell. Throughout the novel, there is no shred of irony, no hint of self-conception, not even the thought that others may find his torments ridiculous. He is utterly self-absorbed. He travels from one location to another to escape his torments, finally settling in Sweden, where he embraces Roman Catholicism and mysticism.
Christine, the narrator’s daughter, on whom he attempts to cast a spell. He later visits her, finding temporary consolation. She directs him on the path to a higher love.
Popoffsky, a former compatriot of the narrator who now wants to murder him. He is one of the narrator’s many tormentors.