Astronaut Boston Low was once NASA's best shuttle pilot. Now he's left the politicking of the space program behind, preferring to spend his time thinking, dreaming and feeding seagulls in the mist of San Francisco Bay. That is, until a mile-wide asteroid suddenly appears in orbit around Earth. Scientists know that a collision—and vast destruction—is imminent. They call on Low to return to space and nudge the menacing new moon into stable orbit, out of harm's way.

It's a mission that leads to an incredible adventure. When Low, prizewinning journalist Maggie Robbins and scientific genius Ludger Brink investigate the asteroid's surface, they turn a key to an anomaly—and are hurtled into a time and place of revelation, mystery and danger: the planet Cocytus.

Once home to an extraordinarily advanced society, Cocytus is now a haunted world of rocky spires, bizarre "museums" and a maze of fantastic, under-ocean tunnels and siphons. For the three human castaways the challenge is to understand the secret of the powerful intelligence woven into the very atmosphere of this mysterious planet. Because on this far side of the universe, solving the mystery of Cocytus and the fate of its inhabitants is the only hope they have of getting home again.