The planet Shikasta, a proxy for Earth, serves as a contested battleground for galactic empires, forcing its inhabitants to navigate a history of cosmic manipulation and impending self-destruction. As an emissary from the advanced planet Canopus, the protagonist Johar observes the planet's development across millennia, attempting to mitigate the corrupting influence of the rival empire Shammat. The narrative is presented through an epistolary framework, utilizing a collection of reports, letters, and historical documents to chronicle the decline of humanity. These records detail the struggle between cosmic forces and the persistent, chaotic trajectory of human civilization toward global annihilation.

This work is widely regarded as a dense and ambitious departure from the author's earlier realist fiction, marking a significant shift toward cosmic allegory. Critics often highlight the intellectual rigor of the archival format, which challenges readers to view human history through a detached, extraterrestrial lens. The narrative's bleak assessment of human progress and its focus on systemic corruption are frequently noted as central to the book's enduring impact. Readers generally approach the text as a complex philosophical exercise that demands patience and careful attention to its layered, non-traditional structure.