As global temperatures soar and the ice caps melt, a biologist finds himself drawn into the primeval, submerged ruins of London rather than seeking escape. Dr. Robert Kerans, a scientist tasked with surveying the flooded capital, experiences a profound psychological shift as the environment reverts to a prehistoric state. While his colleagues attempt to maintain order and salvage what remains of civilization, Kerans feels an increasing, irrational pull toward the encroaching jungle and the rising waters. The narrative, presented through a detached third-person perspective, tracks the internal and external dissolution of the human psyche in the face of a world returning to its reptilian origins.

This novel is widely regarded as a foundational text in the climate fiction genre, noted for its focus on psychological decay rather than traditional action-oriented survival tropes. Critics often highlight the author's ability to render a post-apocalyptic landscape that feels both alien and deeply rooted in the human subconscious. The work is frequently cited for its stylistic precision and its departure from the optimistic technological narratives common in mid-century science fiction. Readers and scholars alike continue to analyze the text for its haunting imagery and its prescient exploration of environmental instability.