Fullmetal Alchemist

...people cannot gain Anything without Sacrificing something. You must present something of equal value in order to gain something. That... is the principle of equivalent trade in Alchemy... We believed that was the Truth of the world when we were young...

I came across this animated series a while back while looking for an anime show to watch and enjoy. Its set in an alternate world coexisting with ours where Alchemy was developed and heavily used as a science as opposed to magic.

It follows the journey of redemption for the Brothers Elric, Edward & Alphonse; who, when faced with the death of their mother as children, erred tragically & disregarded the Laws of Alchemy. This grave mistake cost Edward his left leg & Alphonse, his entire body. In a desperate effort to save his brother, Edward sacrificed his right arm to affix his brother's soul to a hulking, giant suit of armor, and thereafter had to be fitted with advanced prosthetic limbs, for his lost arm & leg. Thus their journey to seek the Philospher's Stone to recover that, which they'd lost, began

Alchemy is a science where one understands the structure of matter. Breaks it down... and then rebuilds it. If used correctly, It could turn plain lead into gold... Since its a science however, the principles of nature still apply. You can only create something of a certain mass, from something of the same mass... It is the principle of equivalent trade...

Now while all this might sound unbelievably dark, for a cartoon - I must point out, its one of the most engaging series to come out in years. For all the sacrifices to be made in equivalent trade, theirs was the greatest. The path the boys chose is fraught with deadly encounters, life lessons and political intrigue. It has deeply sad moments, counter-balanced with lots of anime style humor, and of course - loads and loads of frantic battles. This is helped by the fact that Edward & Al happen to be pretty damn powerful at alchemy. Above all, it emphasizes the bond & loyalty between the two brothers. All these components make a show truly worth watching to the end