The Parasite: A Story

In Short

Professor Austin Gilroy, an exacting physiologist devoted to empirical science, attends a mesmerizing demonstration conducted by Helen Penclosa, an enigmatic West Indian woman. Initial skepticism turns into helpless obsession when Miss Penclosa uses her hypnotic powers to force Gilroy to submit to her will. As her control deepens, she manipulates him into embarrassing public outbursts, bizarre criminal acts, and the destruction of his engagement to his beloved Agatha. Bound by an unseen, terrifying mental grip, Gilroy finds himself locked in a desperate struggle to reclaim his autonomy before he is driven to commit an irreversible act.

The Story

Austin Gilroy is a young, rising professor of physiology whose commitment to objective facts makes him skeptical of psychic phenomena. Attending a gathering hosted by his enthusiastic colleague Professor Wilson, Gilroy meets Helen Penclosa, a fragile, crippled woman visiting from Trinidad who possesses uncanny hypnotic powers. To overcome Gilroy’s resistance, Miss Penclosa places his fiancée, Agatha Marden, into a deep trance and suggests that she abruptly suspend her engagement to Gilroy the following morning. When Agatha carries out the bizarre command without any conscious memory of doing so, a stunned Gilroy admits the reality of hypnotic suggestion and agrees to undergo personal trials to evaluate the phenomenon scientifically.

Initial curiosity quickly degenerates into a nightmare. As Miss Penclosa subjects Gilroy to repeated mesmeric trances, she establishes a powerful mental grip over him. Gilroy discovers to his horror that Miss Penclosa has fallen in love with him. Though he finds her physically unappealing and loathes her influence, he experiences uncontrollable, terrifying impulses to seek her out, sit holding her hand, and profess affection. Recognizing the danger to his honor and his upcoming marriage to Agatha, Gilroy attempts to break off the experiments and avoid her.

Distance offers no protection against Miss Penclosa's reach. Operating from afar, she projects her power directly into his mind, driving him into states of uncontrollable restlessness. To resist the compulsion to walk to her home, Gilroy resorting to locking himself in his room and throwing the key out the window. Furious at his rejection, Miss Penclosa turns her power toward his destruction. Gilroy suffers mysterious blackouts during which his body is hijacked to perform shameful acts. He acts out in public, vandalizes property, attempts a late-night break-in at the local Bank of England branch, and ruins his standing at the university, leading to the suspension of his lectureship. Isolated from colleagues who dismiss his ordeal as brain congestion or exhaustion, Gilroy realizes he is battling a mental parasite.

Driven to the edge of madness and despair, Gilroy decides that he must destroy his tormentor to save himself and protect Agatha. Arriving at Agatha’s house during a blackout, he comes to his senses just in time to discover a bottle of vitriol in his hand, realizing Miss Penclosa was forcing him to disfigure his fiancée. Enraged, Gilroy rushes directly to Miss Penclosa’s residence to end her life with his bare hands. Upon forcing his way into her room, he finds that Miss Penclosa has just died, her death finally severing the invisible chain that bound his soul.

How It Unfolds

A triumph of science Professor Austin Gilroy celebrates the return of spring and his academic success as a young professor of physiology, while maintaining a healthy skepticism toward his colleague Wilson's obsession with psychical research and mesmerism.

The incontrovertible test At a gathering, the visiting mesmerist Helen Penclosa hypnotizes Gilroy's fiancée, Agatha, forcing her to temporarily break off their engagement the next morning, an act that shatters Gilroy's disbelief and draws him into personal experimentation.

The creeping trap As Gilroy allows himself to be hypnotized repeatedly for scientific note-taking, Miss Penclosa forms an unrequited passion for him, using her mesmeric power to force romantic advances that leave him horrified by his loss of self-control.

The battle for willpower Realizing the danger to his virtue, Gilroy tries to break off contact, but Miss Penclosa exerts her influence across distances, forcing him to lock himself in his bedroom to prevent his own feet from carrying him back to her.

A life undone Miss Penclosa retaliates against his defiance by mentally hijacking Gilroy during nocturnal trances, driving him to commit scandalous acts, attempt a bank burglary, and suffer public disgrace that leads to the loss of his university position.

The ultimate outrage After coming to his senses at Agatha's house holding a bottle of vitriol intended to disfigure his love, Gilroy realizes Miss Penclosa is using him as a puppet for violence and rushes to her quarters to kill her, only to discover she has died moments earlier.

The People

• Austin Gilroy: A thirty-four-year-old university professor of physiology who prides himself on his cold, empirical approach to nature. He wants to maintain his academic prestige and marry his beloved Agatha, but his scientific curiosity traps him in a web of mesmeric influence. By the end, his calm rationality is replaced by a desperate, vengeful determination to reclaim his mind.
• Helen Penclosa: A small, frail West Indian woman with a crippled leg and sharp, green-gray eyes that conceal an immense mesmeric power. She desires Gilroy's love and submission, using her hypnotic influence to control others. Rejection transforms her passion into cruel malice, leading her to systematically dismantle Gilroy's life.
• Agatha Marden: Gilroy’s sweet and conventional fiancée, who represents his ideal of domestic happiness. Unwittingly used as the initial test of Miss Penclosa’s hypnotic power, she remains supportive and trusting throughout Gilroy's apparent mental breakdown.
• Professor Wilson: An enthusiastic researcher of psychology and occult phenomena who seeks scientific validation for mesmerism. His obsessive desire for research data blinds him to the immediate human dangers facing his colleague.

In Its Own Voice

"Every year nature readjusts the whole machine."

In the opening entry, Gilroy expresses his strictly mechanical view of human biology as he welcomes the arrival of spring outside his university laboratory.

"A second soul had stepped in, as it were, had pushed her own aside, and had seized her nervous mechanism..."

Gilroy reflects in horror after seeing Agatha forced into an involuntary action by a remote hypnotic suggestion, realizing the terrifying extent of mesmeric control.

"In the home of knowledge I am weighed down and tortured by a power of which science knows nothing."

As Miss Penclosa's attacks dismantle his sanity and reputation, Gilroy laments his absolute isolation within an academic community that refuses to believe his ordeal.

What It's Really About

The Parasite explores the fragility of human autonomy and the terror of losing control over one's own mind and body. Through Gilroy's descent, the narrative critiques the hubris of late Victorian scientific rationalism, demonstrating how easily intellectual pride can be dismantled by forces beyond its empirical framework. The novella captures anxieties regarding psychological invasion, suggestion, and the hidden depths of the human psyche that defy conventional academic categorization. At its core, the story questions whether an individual's moral character can withstand an unseen, invasive force that manipulates human agency from within, framing hypnotic control as a literal parasitic infection of the soul.

Why Read It Today

Modern readers fascinated by psychological horror and Victorian Gothic fiction will find The Parasite a tense, fast-paced exploration of mental invasion. The novel's diary format creates an claustrophobic reading experience, directly capturing Gilroy’s psychological deterioration as his disciplined scientific mind unravels. The story moves with rapid urgency, maintaining a tight focus on the struggle between willpower and unseen coercion.

While the prose is accessible and direct, readers should note that the novella reflects late nineteenth-century attitudes toward physical disability and foreign exoticism, often framing Miss Penclosa's physical impairments and West Indian background with sinister undertones. Additionally, Professor Wilson's technical jargon and the period's pseudo-scientific debates on animal magnetism may feel dated to contemporary audiences. Nevertheless, the central horror—the absolute violation of one's consciousness and the helplessness of being trapped inside a hijacked mind—remains deeply disturbing and resonant today.