Mainspring is the story of a young clockmaker's apprentice. Visited by the Archangel Gabriel, he is told that he must take the Key Perilous and rewind the Mainspring of the Earth. It is running down, and disaster will ensue if it's not rewound. From innocence and ignorance to power and self-knowledge, the young man will make the long and perilous journey to the South Polar Axis, to fulfil the commandment of his God.