The Towers of Titan: A Machine Older Than Memory

On Saturn's largest moon stands a structure that has been running longer than human civilization has existed. Its towers rise from frozen plains beneath the looming shadow of Saturn, and inside them, alien machinery hums with relentless purpose. No one knows who built it. No one knows what it is meant to do. And after years of investigation, the greatest minds of Earth are still guessing.

Dr. Sidney Lee once came to Titan certain he could solve it. Instead, the mystery nearly broke him. Now ...