Ed and Al arrive in East City to see Colonel Mustang and discuss the situation in Reole with him. Curious as to how Father Cornello had managed to create a chimera despite being a non-alchemist, the boys wonder if further research into chimeric alchemy could lead to a way to restore their bodies. As repayment for their work in Reole, Roy introduces them to to Shou Tucker, a State Alchemist specializing in creation of chimeric alchemy who had earned his certification two years prior after producing a chimera capable of human speech. However, Mustang informs Ed that the creature had only said "I want to die" and did not live very long afterward. Edward explains his intentions to Tucker and, impressed with Edward's ability to survive Human Transmutation and succeed at Soul Binding at such a young age, grants the boys access to the multitude of bio-alchemical texts in his private home library. While Edward delves into the books, however, Alphonse becomes acquainted with Tucker's young daughter Nina and their dog Alexander, eventually dragging Ed into their merriment. Unable to find the information they need by sundown, the brothers resolve to return the next day and continue their research, but as they leave, their escort 2nd Lt. Jean Havoc relays a message from the Colonel to Shou Tucker - saying that the "Sewing-Life" Alchemist's yearly assessment is approaching. When young Nina asks her father to explain, he tells her that a State Alchemist must submit the results of his or her research once a year in order to qualify for further grant money and that, since his previous year's assessment didn't go very well, this upcoming appointment is his last chance to remain in the State Alchemist program. Nina is confident in her dear father's abilities, but Shou is unsure and worries that he may lose everything.

The Elric brothers return the next day to continue their studies, but when Nina reveals how lonely she has been since her father became engrossed in his research, the boys remember how their own father had done the same and decide to spend the day playing with her. Meanwhile, Shou struggles desperately to draft a satisfactory assessment report.

Back in Central City, Lt. Colonel Maes Hughes - who has been placed in charge of the investigation regarding the Scarred Man's series of murders targeted at State Alchemists - discusses the case with Major Armstrong, who suggests that the killer's motive may be to punish State Alchemists for breaking away from the alchemist's code of service to the people in exchange for government licenses and funding. Just then, they receive word that a man fitting their quarry's description was noted to have been seen at the Central Train Station, prompting the Lt. Colonel and the Major to suspect that the killer may have fled the city.

At the Tucker house, Shou explains to the Elrics that in the days before he achieved his State certification, he was so poor that his wife left him and that he would do anything to keep from returning to such a state. When Nina comforts him, Shou offers to spend the next day playing with his little girl and Nina joyfully accepts. But when the boys return the following day, they are surprised to discover the house is virtually void of sound. In a back room, they find Shou working on a new creation - a second chimera capable of human speech. Tucker shows off by teaching the beast to say "Edward", but when the creature calls Ed "big brother" without prompt, Ed is horrified and asks Tucker again how long ago he received his license and how long ago his wife had left him. When Tucker responds to both queries with "two years ago", Ed asks a third question - demanding to know where Nina and Alexander have gone. Tucker remarks that Ed catches on quick and Fullmetal attacks him furiously, explaining to Alphonse that that the creature before them was created by alchemically fusing Nina and Alexander together, just as Shou's first talking chimera was forged from his mysteriously absent wife. When Sewing-Life dejectedly confirms as much, Edward furiously condemns Tucker for playing around with people's lives, but Tucker responds by accusing Fullmetal of being the same as him - of playing around with his brother's life and performing Human Transmutation simply to test his own abilities. Hearing this, Edward flies into a rage and begins beating Tucker savagely with his automail fist, causing Alphonse to restrain his brother physically to keep Sewing-Life from being beaten to death. Alphonse apologizes to Nina, saying that neither he nor his brother has the ability to undo the damage her father did to her, and the boys report the situation to East City HQ.

At headquarters, Edward discusses the situation with Colonel Mustang and acknowledges that, even though - as a State Alchemist - he will likely see a great deal more evil and may even be ordered to commit atrocities of his own as a "human weapon" of the military, he will continue to press forward on his path until he has achieved his ultimate goal. But, at the same time, he acknowledges that he is only human despite his abilities or his position and that he was unable to save even one little girl. The Scarred Man arrives at the Tucker house, while Shou and Nina sit under house arrest, and declares to Shou that, as an alchemist who has strayed from the path of God, he must die. Placing his right hand on Tucker's face, he displays his strange ability once more and destroys Shou's body from the inside. Noticing Nina, the stranger apologizes for what has been done to her and repeats the process, asking her to go in peace. As the Scarred Man exits, he asks God to care for the two souls that he has just sent to the afterlife and removes his sunglasses to reveal red eyes.