In the small town of Resembool, Dr. Pinako Rockbell has just finished up repairing a patient's prosthetic leg, when Den begins barking, alerting her of Ed and Al's return to their hometown. The boys introduce Pinako to Major Armstrong, and after a mini war of short insults between Ed and Pinako, Winry makes her presence known via flying wrench to Edward's head, scolding him for not calling before showing up unannounced.

After filling the Rockbell's in on their recent adventures, the boys explain the rush they're in to get to Central and find out more about the Philosopher's Stone. Pinako and Winry let them know they'll be finished with the work in three days, so the boys do their best to rest up despite Edward's impatient tendencies. Al suggests Edward visit their mother's grave while he has the opportunity.

Major Armstrong helps out by chopping firewood and he and Pinako discuss the boy's well-being while Edward's gone. After Armstrong's comment about how strong the boys are, Pinako recounts the night they attempted to transmute their mother, wondering where all Edward's strength comes from, and how she worries what will happen to Ed when he encounters an obstacle he is unable to overcome. Explaining that the boys are like grandchildren to her, she mentions the absence of their father, and that none of them know if he is even alive or not. Armstrong asks about Winry's parents, and she explains that they were surgeons who volunteered in the Ishbalan war and never came back, having died in battle. She thinks it ironic that the war that took all their family from them, also resulted in so many people needing prosthetics, that is what keeps food on their table. At that, she decides it's time to start dinner and invites Armstrong to eat with them, as well as stay over since Ed and Al have nowhere else to stay themselves. Pinako lets him know that the day Edward received his military license, he and Al burned down their house so they wouldn't be able to turn back from their journey before it's end.

When Ed's new automail is complete, Pinako and Winry attach them to his body, an incredibly painful process in which the nerves reconnect with his false limbs. Winry tries to explain that to make it more rust resistant she used a higer percentage of chrome, resulting in a less durable metal, however Edward has already dashed off to repair his brother. Once that's taken care of, the two of them begin sparring to break in their new bodies, a task which shirtless Major Armstrong is more than happy to assist with.

After working up a sweat, the boys and Armstrong stop for a nice familial dinner, and then it's off to bed for Edward, while Alphonse tells the Rockbells about Edward's kindness at Youswell, and how he's glad to have some kind of a home with Pinako and Winry. All Alphonse's mushy talk touches Armstrong, who quietly weeps out in the hall with his hanky. The next day the boys are ready to go and say their goodbyes. After they're gone Pinako and Winry get back to work cleaning up their work stations, when Winry makes the unfortunate discovery of a lone bolt belonging in Edward's automail that isn't where it's supposed to be.

Having finally arrived in Central, the brothers are greeted by Second Lieutenant Maria Ross and Sergeant Denny Brosh to escort them, as Major Armstrong is to report to Central Headquarters. Edward is less than ecstatic at the idea of more bodyguards, but with the assassin Scar still on the loose, the military doesn't want to take any chances in regards to the boy's safety. On the way to the library, Sergeant Brosh asks Alphonse why he wears armor, and he and Ed nervously respond that it's a hobby. They all arrive at the impressive National Central Library, and walk to the First Branch where Ed and Al have been headed, only to discover that it had burned to the ground just the day before.

Meanwhile, in East City, Colonel Mustang is confronted by Major General Hakuro about the Scar incident, berating Mustang for not having resolved this conflict yet. Once he's gone, Mustang explains to Hawkeye and Havoc that Hakuro is just bitter that he's acheived the rank of Colonel so young and is paranoid about him one day taking his position in the military. However, Mustang is also anxious to catch Scar as it will make him look good if he can catch a criminal causing so much trouble in Central from East City, as he is willing to do anything that will help him get promoted to president.

Right above the Colonel's head, Lust returns from burning down the First Branch of the library in Central, when suddenly Gluttony picks up Scar's scent and is in ecstasy when Lust grants him permission to eat the Ishbalan. Scar is wandering the sewers when he is suddenly attacked by Gluttony, causing mass destruction to the streets and bridges above them.

Back in Central, Edward is doing his best detective work in finding any of Marcoh's research that may have been spared the fire, and is referred to a bookworm named Sheska. When they arrive at her home, they rescue her from a pile of books that had toppled over on top of her, her house is filled from floor to ceiling with nothing but books. She explains that reading on the job is what got her fired from the library, and that she does remember reading Marcoh's notes, which means they were indeed in the branch that burned down. Edward is crushed again until she mentions her photographic memory and her ability to reproduce any book she's ever read word for word. After five days she has completely recreated Marcoh's notes for Edward, which turn out to be a very large recipe book. Ross and Brosh are aghast at still not having recovered Marcoh's notes, but Edward is beside himself with excitement, much to their surprise. Before he goes he instructs Ross to take out what appears to be a ridiculously large sum of money from his research grant funds as payment to Sheska.

Back at headquarters, Edward explains to Brosh that alchemists don't want all their secrets getting into the wrong hands so they keep their notes in code. So, what looks like a simple book of recipes is actually all of Marcoh's findings on the Philosopher's Stone, and all they have to do is decode it, which they have yet to do after a week of working as hard as they can. Sheska comes to thank Edward for the large sum of money and expresses her gratitude for having been useful for something. Suddenly, Lieutenant Colonel Hughes drops by while on a break, and mentions how the fire at the branch really slowed down a lot of their invesitgations due to the fact that they stored most of their records there. Ed and Al point out Sheska's ability and Hughes hires her on the spot, dragging her away to begin work immediately, while Ed gets back to work decoding Marcoh's notes.

After ten days of working, Edward and Alphonse finally decipher the code, and discover that the main ingredient for creating a Philosopher's Stone is a living human being.

Disgusted at discovering that multiple human sacrifices are needed to create even one Philosopher's Stone, Edward asks Ross and Brosh not to mention any of what they've heard.

Back in East City, the military investigates the bridge that appears to have been blown up from the inside, where Hawkeye and Mustang recover Scar's bloody jacket. Without a body though, they can't know if he's dead or not so Mustang orders Havoc to keep looking until they find either Scar, or a body, because he can't relax enough to go on another date until they do! Nearby, Lust and Gluttony look on, as Gluttony cries over his lost meal. Lust says she'll return to Central to inform Father of the incident.

Cooping themselves up in their room, Ed and Al lay about, all their energy drained from working so hard just to discover the truth about the Philosopher's Stone. They wonder if they'll have to stay the way they are for the rest of their lives, and Ed is about to confess something seemingly important to Alphonse, when Major Armstrong breaks the door down after forcing Ross and Brosh to tell him what is troubling the boys. Brosh notices Ed's automail and Ed lies about it being a mishap from the war, and that it's why they wanted the Philosopher's Stone. Suddenly, Edward remembers that Marcoh told him to find "the truth that lies within the truth" and realizes there must be something more to the Philosopher's Stone than he thinks.

The five of them get out a map of Central, and locate the four laboratories military research was taking place in. Edward notices a building and Ross tells him it used to be a fifth laboratory but was shut down. Edward knows that's the place they need to go because it's located next to a prison. He realizes the military would have simply used the bodies of prisoners scheduled to be executed in experiments related to the Philosopher's Stone. In order to find out if the goverment is involved in diabolical activites, or if the research department is acting of their own accord, Alphonse suggests they contact the head of the department, who Armstrong tells them is Brigadier General Basque Grand, but that contacting him is impossible because he was murdered by Scar a few days before. In case anyone in the military higher up that Basque Grand is involved in the matter, Armstrong decides to research on his own and get back to them. Until he knows more, Ross and Brosh are to keep quiet about it, and the Elric brothers are to stay put in their room.

As soon as they can, the boys escape their room and make their way to Laboratory 5, and are surprised to find a guard protecting a supposedly abandoned building. They climb over the building and Alphonse has to wait outside because only Edward is small enough to crawl through the air duct to sneak inside. As Alphonse waits outside for his brother, he is suddenly attacked by a very strange looking fellow who identifies himself as Number 66, and is very excited about trying to kill Al. Inside, Edward comes across a large room with a huge transmutation circle on the floor and is approached by another strange figure who introduces himself as Number 48, and proceeds to attack Edward quickly, surprising the boy with his speed. They battle heatedly and as Edward makes contact with his left leg, he realizes Number 48 is hollow inside from sparring with Al. Edward remarks that he's disgusted there are other people who would purposely bind a soul to a suit of armor, so Number 48 decides to tell Edward more about himself. "48" was his number on death row, and in life he was known as a serial killer called "Slicer" who was supposedly executed two years ago. He shows Edward where his blood seal is, and they resume their battle.

Chapter 12: The Definition of Human --- Ningen no Teigi
Originally Published in Shounen GanGan July 2002

Back in their room, Ross and Brosh are furious that the Elric's have run off to Laboratory 5 despite being warned not to, and fearing the Major's wrath decide to chase after and recover the boys themselves.

Meanwhile, Ed and Number 48 are still going at it, when Edward suddenly remembers Winry's warning about the strength of his new, lighter, automail. Trying to do his best to end the battle quickly, all Ed does is recklessly get himself injured. Outside, Alphonse is faring much better against Number 66, stealthily dodging his attacks, much to 66's chagrin. However, when Al trips over a rock, Number 66 takes the opportunity to wedge his knife into a joint in Al's arm, and is caught off guard when Al easily snaps the knife in two, and knocks off his head, revealing that he is hollow inside, just like Al.

Number 66 proceeds to tell Al the story of Barry the Chopper, a butcher who loved to chop up meat, and learned he also loved to chop up people. But eventually Barry got caught and was said to be executed, when in fact his life was spared if he promised to guard a certain laboratory. Number 66 then reveals that his soul has been trapped in his armor and he is in fact, Barry the Chopper and Barry is less than pleased at Al's reaction when his head fell off. Alphonse shows Barry that he is hollow inside as well, and explains how Ed transmuted his soul into a suit of armor to save him. Barry scoffs at Al's mention of his brother and puts forth the idea that when Al's soul was transmuted, his memories were as well. Since you can't see a soul, how can you prove it exists? Just as Alphonse questions Barry about his own existance in that aspect, an unfortunate guard comes around the corner, and Barry nonchalantly slices the poor man's head off, picking up the conversation right where they left off. Barry explains that his love of killing is all the proof he needs of his existance.

Back inside the laboratory, Edward gets the upperhand and separates Number 48's head from his body without destroying his blood seal. Ed questions him about the Philosopher's Stone and he refuses to answer, saying he hasn't lost the battle yet, when his body attacks Edward from behind. It turns out "Slicer" was actually a pair of killers who were brothers, and they were both bound to the same suit of armor.

Edward is in bad shape at the start of the second round of this fight, and flashes back to his encounter with Scar, when he thought his was going to die, and mangages to muster enough strength to blast through Number 48's body, separating the torso from the legs. Having won, Edward demands they tell him about the Philosopher's Stone. When they refuse and tell Ed to kill them, he surprises them by saying that he won't be a murderer, explaining that if he thought they were less than human, it would mean he thought the same thing about his little brother, who is the same as them.

Something in Ed's story touches Number 48, and as a parting gift, decides to tell Ed what he can. He doesn't know anything about the actual Stone itself, but does know about the people who created it. However, just as he is about to divulge the information, Lust and Envy unexpectedly enter the scene.

There is an upsurgence of gossip around the military base as to who is stronger; the Flame Alchemist, or the Fullmetal Alchemist. Fuhrer Bradley finds the topic interesting and the match is coordinated by Lieutenant Colonel Hughes. In front of a huge crowd of military folk, Roy and Edward engage is a massive battle, each gaining the upper hand in turn, all the while causing mass destruction to their surroundings as well as the crowd. While it looks promising for Edward, Roy reveals a trump card at the last moment and emerges victorious. However, his only reward is overseeing the cleanup from their reckless display.