At 3 AM on a Tuesday in March, radio astrophysicist Dr. Mara Voss detects something impossible: a perfectly clean, mathematically precise signal at 0.3 hertz, emanating not from space — but from the direction of Antarctica.It has been broadcasting, unnoticed, for at least eleven years.When Mara assembles a small team of specialists and descends beneath the East Antarctic ice sheet, what they find below a sealed subglacial lake defies every framework science has for understanding Earth's history. The bedrock is structured. Engineered. Composed of materials that should not exist. And the signal it generates is not noise — it is data. A seven-level hierarchical information architecture, broadcasting a continuous status readout of a planetary-scale system that has been running, silently, for longer than human civilization has existed.Something built this. Something that was here before us.As an interagency team closes in to contain the discovery, Mara and her colleagues have seventy-two hours to document, decode, and publish their findings before the most significant scientific discovery in human history disappears into classification. But the deeper they go, the more the signal reveals — and the more it becomes clear that the system beneath the ice has not merely been waiting to be found.It has been waiting for humanity to become something that could hear the question it was asking.Signal Beneath the Ice is a hard science fiction thriller about deep listening, deep time, and what it means to discover that the planet you live on has been keeping a secret for eight hundred million years.