Chapter 11: The Two Guardians

Reeling from the revelation that a Philosopher's Stone is fashioned from living people, and that a single one demands many lives, the distraught Elric brothers beg Brosh and Ross to pretend they never heard it. Meanwhile, in East City, military police recover Scar's jacket near the wrecked sewer where he tangled with Gluttony, and Mustang's unit is called out to investigate. Hawkeye reads the bloodstains and concludes the serial killer must have fled badly hurt, while nearby Gluttony sulks that his meal slipped away. Lust consoles him and makes plans to head back to Central and report the development to their Father.

In the capital, the brothers mope in their hotel, cursing their luck and doubting they will ever reclaim their old bodies. Edward begins to raise something weighty he has long been afraid to voice, only for Major Armstrong to burst in, having pried the whole story out of Brosh and Ross. As the major weeps over the boys' misfortune, Ed suddenly recalls Marcoh's cryptic parting hint about a truth lying behind the truth, and takes fresh heart. Poring over a city map that marks Central's four working alchemy laboratories, he flags a supposedly closed Fifth Laboratory, reasoning it is the likeliest site for Stone production given its position beside Central Prison, whose death-row inmates could quietly serve as the necessary living material.

Armstrong explains that Lab 5 once fell under Brigadier General Basque Grand, who, along with other alchemists who may have shared the secret, was recently killed by Scar. Wary that the trail could reach someone of high rank, the major decides to look into it discreetly and orders the boys to remain in their hotel and stay clear of the site. Under cover of night, though, they slip out anyway and spot a soldier posted at the supposedly abandoned building, proof it is anything but idle. Judging the narrow vents the only quiet way in, Edward heads inside while Alphonse keeps watch without.

Deep within, two shadowy armored figures who address each other as Number 48 and Number 66 stir at the intrusion; 66 sets off after Al while 48 waits for Ed. Confirming the lab still draws power to its lit corridors, Ed presses on and reaches a wide hall marked with an enormous, bloodstained five-point transmutation circle, wondering aloud whether this is where the Stone was made. Number 48 confirms it, emerging from the dark to warn that a trespasser who knows of the Stone cannot be allowed to walk away. Ed transmutes the plating of his automail arm into a blade and, in the clash, discovers that 48 is a hollow suit of armor much like Alphonse. The swordsman reveals he was once the death-row killer known as Slicer, used as a subject in soul-binding experiments, and that his blood rune hides inside his helmet, which Ed must destroy to win.

The Elrics ask their escorts to bury the secret of the Stone, while Hawkeye's analysis of Scar's abandoned jacket confirms he escaped his fight with Gluttony gravely wounded. Marcoh's parting riddle spurs Edward to identify the Fifth Laboratory as the hidden Stone workshop, tied to the assassinated Basque Grand. Defying Armstrong's order, the brothers infiltrate the lab by night and are confronted by its two armored guardians. Ed's duel with Number 48 exposes both fighters as empty, soul-bound suits of armor, mirroring Alphonse's own condition, as Number 66 closes in on Al.

Edward mentions having toured Laboratory 3 shortly after earning his certification without noticing anything unusual, and that Lab 3 was the facility Tim Marcoh had been affiliated with. The chapter offers the first explanation of how blood runes function, binding the iron in a person's blood to the iron of the armored body. Its Japanese title is Futari no Shugosha, and the events were later adapted in both the 2003 and 2009 anime series.