A respectable London physician inadvertently unleashes a malevolent alter ego through a scientific experiment gone wrong. Dr. Henry Jekyll seeks to isolate the dual nature of humanity, but his chemical concoctions result in the emergence of Edward Hyde, a figure devoid of conscience. As Hyde begins to exert control over Jekyll's life, the protagonist struggles to maintain his social standing while concealing the horrific crimes committed by his shadow self. The narrative unfolds through a series of perspectives, including legal documents and personal accounts, which slowly reveal the tragic disintegration of Jekyll's moral identity.

Readers frequently highlight the effectiveness of the novella in establishing the archetype of the split personality in literature. Discussion often centers on the moral implications of Jekyll's experiment and the societal pressures of the Victorian era that necessitate such repression. Critics often point to the stark contrast between the orderly world of the protagonist and the chaotic, violent nature of his counterpart. The pacing is noted for its steady escalation, moving from a curious mystery to a harrowing psychological study of self-destruction.