FullMetal Alchemist

Edward and Alphonse Elric are two brothers gifted with the ability of alchemy, the science of taking one thing and changing it into another. However, alchemy works on the theory of Equivalent Exchange -- for something to be created, something else of equal value must be sacrificed. When their mother dies, Edward decides to do the unthinkable -- bringing her back to life by preforming Human Alchemy. However, both Edward and Alphonse know that by doing so they will be breaking one of Alchemy's biggest taboos.

Believing they have nothing more to lose, Ed and Al goes ahead with their plan and make their attempt. Unfortunately, something goes horribly wrong and in the process Ed loses his leg while Al loses his body. Ed manages to save Al by attaching his spirit to a suit of armor, but at the cost of his arm.

Now determined to correct what they have done and get their bodies back, the brothers decide to become State Alchemists to gain access to the State's enormous library on alchemy. There, they learn of the legendary Philosopher's Stone, an item that could help them get their bodies back. They soon learn, however, that they are not the only ones after the Stone as even the military has their own agenda for its use.