The imaginary nation of Amestris serves as the setting for Fullmetal Alchemist. Alchemy is one of the most widely used sciences in this universe; practitioners who work for the government are referred to as State Alchemists and immediately receive the rank of major in the armed forces. Alchemists have the power to transform patterns known as transmutation rings into nearly anything they want. However, in order to comply with the Law of Equivalent Exchange, they must offer something of like worth in return. Alchemists are only prohibited from transmuting humans and gold.
There has never been a successful transmutation of a human being; those who try to do so end up with an unnatural mass after losing a piece of their body. It is widely stated and assumed that Truth is a personal God who punishes the haughty. Attemptees are met with Truth, a pantheistic and semi-cerebral deity that tauntfully regulates all alchemical use. Truth’s nearly featureless appearance is relative to the individual with whom Truth converses.