In the world of Amel, drugs hold the key to magic. Humans are unable to control the powers of the Kosim unless they imbibe the dangerous substances collectively known as Agha. With the Agha, found in caves beneath the Sheath, humans drove the spirits of Amel, called the Mweya, to the farthest reaches of the world. Agha can only be grown in the Sheath. Many have tried to grow it outside, but the spores of Agha create holes in the fabric of reality, and terrible things come through. It is only in the Sheath where these holes are contained by some unknown force in the darkest corners of the caves. Amel is a bitter place to live in. The world is swinging towards another ice age, and the people are hardy and resentful. Religions, nations, and creeds clash on the battlefield with aid from black-dust power and Agha. Somehow, the Magisters of the Sheath manage to maintain neutrality in these conflicts and keep the Sheath as a free city. But the nations of the world have their eye on the Sheath and covet its monopoly over Agha. What's more, the Mweya have begun to creep back into the world. As these near-gods take back the land and the Magisters of the Sheath seem unconcerned, diplomatic pressure rises to free the supply of Agha to the world.