The Seventh Tower is a series of six books written by Garth Nix, the result of a joint partnership between Scholastic and LucasFilm. The series follows two children from distinctly different societies in a world blocked from the sun by a magical Veil which leaves the world in complete darkness.
Tal is a Chosen from the Castle, and Milla is an Icecarl from the Ice. Together they discover that an evil, long thought to have vanished, once more threatens their world, slowly and secretly letting its presence be felt. A pact was broken, and a war dormant for two thousand years is rekindling. Danger looms, and it is up to these two children and a small band of unlikely heroes to save their Dark World.
The books are as follows:
The series was born when an editor from Scholastic emailed Nix saying he liked Nix's previous book Sabriel, and that he'd be glad to work with him on something in the future. A few months later, Nix received another email from the editor saying Scholastic and LucasFilm were working to create a new fantasy series. He asked if Nix would be interested, to which Nix replied that he might be. They discussed it back and forth through email.
Several months later, Scholastic and Lucasfilm gave Nix a general list of "influences and ideas" to base the series on. However, Nix was still given much freedom to expand from it to create a story of his own. "In a way, each of the ideas and influences on the original list was like a seed," says Garth Nix. "The seeds were planted in my imagination and things have grown from them, and I have helped them grow and shaped them to fit into the story." Among the points included on the list was a world "where it is always night for some reason" and characters with magical companions of some sort.
The series was written at a rather quick pace, as fast as three to four months per book. By June 2000, the first book entitled The Fall came out. The Seventh Tower has since gone on to sell more than one million copies in the US.
These are the "Masters of Light and Shadow", possessing magical control over Sunstones and shadows. Sunstones have their own light and heat. They are grown from crystals, or sun seeds, originating in Aenir. They are "charged" by exposing them to sunlight for extended periods of time. The "charging" is done above the Veil in large nets. The larger a stone is and the longer it is exposed to the sun, the more powerful it will be. They are a part of everyday life for the people of the Dark World, used in everything from giving light to cooking food. Chosen children are given weaker Sunstones, compared to the Primary Sunstone which older kids and adults use. However, a Chosen who loses all of their Sunstones is demoted to Underfolk status.