Following his defeat in the war in Heaven, Satan rallies his fallen angels to plot a new campaign of vengeance against God by corrupting His latest creation: humanity. Driven by pride and an unyielding desire for autonomy, the protagonist seeks to undermine the divine order from the depths of Hell. He must navigate the treacherous landscape of Pandemonium while managing the dissent and despair of his fellow rebel angels. The narrative framework employs grand, blank-verse epic poetry to explore the psychological motivations of its central figures and the cosmic stakes of their rebellion.

Readers and critics frequently analyze the work for its complex portrayal of Satan, often debating whether he serves as a heroic archetype or a cautionary figure of pride. Discussion often centers on the technical mastery of Milton's blank verse and the philosophical depth regarding the nature of evil and human agency. Many highlight the atmospheric intensity of the descriptions of Hell, which remain influential in Western literature. The text is widely regarded as a foundational epic that invites ongoing scrutiny of its theological and political implications.