After Ed wakes up from a nightmare about his mother and Nina, he and Al head to East City HQ to inquire about the fate that awaits Shou Tucker and Nina, but Lt. Hawkeye informs them that while Shou was scheduled to be taken out of traffic and court-martialed, both murdered by an unknown assailant. He goes on to say that he’s heading to the crime scene, but refuses to let the Elrics go because he doesn’t believe they should see it. Lt. Col. Maes Hughes and Major Armstrong arrive from Central to investigate, lamenting that the killer is one step ahead of them, causing Col. Mustang to question why they sound like they expect a murder.
In Reola, someone who looks like Father Cornello is driving the townspeople to war, with the resort fanatics brutally attacking the skeptics and vice versa. As the city becomes a war zone, Lust and Gluttony watch from the church steeple, mocking human folly and predictability. They are joined by the fake Cornello, who joins in their taunting, and the three note how the people of Reole have completely fallen for their plan despite Fullmetal’s interference. They note that people never learn, blindly resorting to hatred and bloodshed at the slightest provocation, and a person who looks like Cornello suddenly transforms into a new form at Lust’s command, revealing himself to be Envy, the third of these mysterious agents. Unfortunately, this transformation is witnessed by Cray, who demands to know where the real Cornello has gone. To silence him, Lust and Envy have the Gluttony devour the horrified cleric alive while they discuss the goings on in East City. While neither of them care if Tucker is dead or alive, they do consider the dangers of letting this elusive killer roam free around Roy Mustang or Edward Elric; Lust is still outraged that Fullmetal stopped their plan to Reole, but claims they can’t let him die because he’s an important “human sacrifice”.
In East City, Hughes and Armstrong explain to Mustang and Hawkeye that they have named this serial killer “Scar” because his only identifying mark is a large scar on his forehead. Scar is responsible for killing five state alchemists in the capital and ten nationwide, and Mustang is shocked to hear that a veteran Brigadier Grand has been killed. Maes suggests that Roy take measures to protect himself since only Flame and Sewing-Life were prominent in the east. City, but Roy suddenly remembers that Fullmetal is also currently in the city. Ed sits in the rain with Al and notes how their teacher taught them that even death is part of the alchemical flow and that they should embrace it. Thinking of his mother and Nina, Ed wonders how he could be so foolish as to hope to overturn such a basic law of nature, even though he suffered so much for it. However, just then the boys are attacked by Scar, who can destroy anything his right hand touches, the boys flee the city with the killer on their heels, only to be stopped when a scarred man traps them in an alley. . Forced to fight, the boys attack but find themselves defeated when Scar tears a gaping hole in Alphonse’s side, immobilizing him and obliterating Ed’s arm with automail in a flash. Ed collapses to the ground as the immobilized Alphonse, terrified for his brother’s safety, screams desperately from his spot on the sidewalk. Frozen in shock and despair, Edward asks Scar if Alphonse is also one of his assassination targets. Scar explains that while he will kill anyone who gets between him and his goals, Alphonse is not one of his priorities, so Edward offers his own life in exchange for Scar’s word that Al will escape unharmed. Scar agrees to Fullmetal’s terms and moves in for the kill, but Alphonse – vehemently against his brother’s resignation – pleads with Ed to escape.
Fortunately, Scar is stopped by the timely intervention of Colonel Mustang and his forces. Roy declares Scar under arrest for his crimes, but Scar responds that alchemists – who desecrate God’s plan by changing the shape of natural things – are criminals who deserve punishment. Spurred on by Scar’s words, Roy attempts to confront the killer with his powers, but is saved and reminded by Lt. Hawkeye that his Flame Alchemy doesn’t work properly in the rain. While Scar is distracted by Roy’s actions and his own threats, Major Armstrong attacks from behind and formally introduces himself as “The Alchemist of the Strong Arm”. Armstrong and Scar engage in battle, and the Major, observing and analyzing the alchemical assassin’s counterattacks, deduces that the mysterious assassin’s “power” is actually alchemy with the “reconstruction phase” omitted, leaving all matter transformed by him into the second phase – the “deconstruction phase.” While Roy wonders how an alchemist can stand up to other alchemists on principle, and 2nd Lt. Havoc explains to Edward that Scar is the one who killed the Tuckers, Scar realizes that Strong Arm is a much more dangerous opponent than first thought and changes his attack. pattern to utilize major wide swings. But when Armstrong suddenly withdraws from the fight, Scar realizes that the frequent opening was intentional – a decoy to distract him while Lt. Hawkeye prepared to open fire with his rifle. Scar manages to dodge her shots, but a bullet hits his face and knocks off his sunglasses, revealing his irises to be red. When Armstrong and Mustang saw this, they recognized Scar as Ishvalan. Not expecting so many enemies and unexpected twists, Scar cut his losses and deconstructed the street below him, escaping into the sewers. Ed scrambles to Al’s side to check on him as the others marvel at the younger Elric’s hollow constitution, but Alphonse angrily and violently berates his brother for giving up on death while he still had a chance to live, and orders him never to do it again.
Back at HQ, Mustang explains to the Elric brothers that the Ishval region to the east was the center of a civil war that began thirteen years ago when an American soldier accidentally shot an Ishvalan child. After seven years of fighting, state alchemists were sent to Ishval to end the war by eradicating all Ishvalans in the region. As one of the state alchemists involved in the extermination, Col. Mustang claims that there may be some justice in Scar’s murder, but Edward refutes this, saying that Scar is merely masquerading his own revenge as justice. When Roy vows to hunt down and dispose of Scar, Edward claims that his lost hand makes it impossible to repair Al’s armor while guaranteeing the integrity of his bound soul. Therefore, he states that his next step is to visit his auto mechanic.