An expedition to the frozen wastes of Antarctica uncovers the terrifying remnants of an ancient, non-human civilization that defies the laws of biology and history. The protagonist, William Dyer, leads a team of researchers who discover bizarre, fossilized specimens that suggest a history of Earth far older and more alien than previously imagined. As they venture deeper into the mountains, they encounter physical evidence of a lost race whose existence threatens the sanity of the explorers. The narrative is presented as a formal, urgent report intended to warn future expeditions against encroaching upon these forbidden, desolate peaks.

This work is widely regarded as a foundational text in the development of cosmic horror and the Cthulhu Mythos. Readers and critics frequently highlight the effectiveness of the slow-burn pacing and the vivid, unsettling descriptions of alien landscapes. The narrative is often cited for its ability to shift from a grounded scientific expedition into a descent into madness and cosmic realization. While the prose style is dense and characteristic of the author's era, it remains a significant influence on modern speculative fiction and horror writers. The story continues to be analyzed for its unique blend of scientific inquiry and supernatural terror.