When Lt. Hawkeye opens fire on Gluttony, Colonel Mustang on the other end of the line panics and rushes out of his office. Meanwhile, Ling explains to Alphonse and Winry that all the current events are part of Mustang’s plan to smoke out the people who were secretly involved in Lab 5, according to Barry Chopper. Al decides to join the mission in hopes of finding out something about what happened to Hughes, and promises Winry that he will return to her safely.
In a tower near the safe house, Hawkeye battles Gluttony, who seems completely unharmed by her merciless gunfire. Just as the ravenous monster prepares to eat her whole, Black Hayate and Fuery intervene and distract Gluttony long enough to free Riza and launch a second round of bullets. Still, Gluttony refuses to be subdued until Roy bursts onto the scene and blasts the creature from the tower with a fiery blast, expressing his relief that he was able to help in time. However, Hawkeye is less than pleased and berates Mustang for revealing himself to the enemy. Mustang and Hawkeye discover that Barry’s human body is on the move and get to ground level, securing the car and picking up Havoc to follow, only to suddenly run into Alphonse who has come to help. As Barry chases after his body, the four in the car follow his trail. Wondering aloud if Gluttony is really dead, Hawkeye states that he continued to attack despite being shot multiple times in his vitals, and Alphonse states that her enemy must have been the Homunculus. Mustang states that such a being cannot exist, but changes his tune when Al reveals his meeting with Greed and explains that these creatures have remarkable regenerative properties. As Roy begins to lament having to deal with such inhuman monsters, Gluttony rises again, his injuries gone.
Barry’s trail stops at the Central Alchemy Lab #3, where Roy states that the lab’s involvement alone has already implicated members of the military command in the ongoing conspiracy, and orders a retreat since they already have what they need. However, Chopper has other plans and invades the facility after his body. Quickly devising a new plan to take advantage of the situation, Colonel Mustang orders everyone else to enter the building and informs the lab staff that he is chasing the fugitive who just entered. Mustang, Havoc, Hawkeye and Alphonse follow Barry’s journey to the underground floor of the facility and split into two groups to search – Jean with Roy in one pair and Riza with Al in the other. However, just as Havoc and Mustang discover the abandoned experimental chamber, they are greeted by Lust, who mockingly berates Jean for betraying her. They notice her Ouroboros tattoo and label her as an enemy, prompting Roy to ask her if she had anything to do with Hughes’ death. When she states that she did not deliver the final blow but was involved, Roy shoots her in the leg and demands that she get down on her knees for questioning. But when her wound heals before their eyes and she declares that it will take more than bringing her to her knees, the two soldiers realize that the woman in front of them is a Homunculus. Amused by how much they know, Lust uses her bladed nails to pry open her chest cavity to reveal the Philosopher’s Stone that acts as her core – its energy powers her regeneration and other powers. Realizing that she only showed them because she doesn’t intend to let them survive, Roy launches an attack, but when Lust splits the upper water pipes with her claws, soaking Roy and effectively crippling his Flame Alchemy, he and Jean are forced to flee the room. Thinking quickly, Roy uses the transmutation ring on his gauntlet to split the water filling the chamber into flammable hydrogen and flammable oxygen, and Jean—on impulse—throws her lighter inside, causing an explosion that engulfs the Homunculus in flame.
Jean and Roy re-enter the room to investigate, but just as Roy warns his mate to look for Lust’s regeneration powers, her fingers burst from the debris and stab Havoc through the stomach. Roy frantically tries to move the fallen and bleeding 2nd Lt. while Lust rises from the ashes, her body quickly reforming. Roy picks up Havoc’s carbine and shoots a hole through her chest and rips out her Philosopher’s Stone, declaring that he will use it to heal Havoc’s wounds. Without her core, Lust crumbles to dust, but before the Colonel can reach Jean’s side, the Homunculus’ body quickly and grotesquely transforms around the stone in his hand before its claws pierce his stomach. Lust rips off Roy’s Flame Alchemy Gauntlet, leaving both men to die while lamenting that such a valuable human sacrifice had to be lost. As he leaves to join the others, Roy orders Havoc not to die in front of him. Outside, Führer Bradley arrives on the scene and informs the soldiers at the gate that he will be entering the building himself to offer support to Colonel Mustang.
Riza and Al finally catch up with Barry in a huge white room with a huge pair of stone doors to find that Chopper has finally mutilated his human body. Barry laments that his human form has disintegrated so deeply, suggesting that binding a soul to an incompatible body is impossible. Hearing this, Al begins to wonder how long he has left before his own soul rejects and separates from its metal vessel. Lust appears on the scene, expressing anger at Barry’s betrayal of his masters and grief at Alphonse’s presence – as it means he will have to kill two Human Sacrifices in one night. Barry lunges forward to attack Lust, but her fingers quickly cut him to ribbons. Turning to the other two, Lust promises to send Riza to Mustang’s side and the lieutenant, stringing the Homuncul’s words together, becomes enraged and opens fire with multiple handguns before succumbing to grief and collapsing in tears over Roy. Lust tries to kill himself, but Alphonse steps in the way and prevents Riza from attacking. As Lust cuts off Al’s armor, Hawkeye begs the young alchemist to run and leave her behind, but Alphonse refuses. Alphonse thinks of Nina Tucker, Hughes and Martel that he won’t let any more of his friends die.
Roy appears at the entrance and praises Alphonse for his statement, and as the armored boy builds a stone barrier to protect himself and the lieutenant, the Colonel unleashes a stream of flames on Lust, finally bringing her to her knees. Shocked and burned, Lust realizes that the Flame Alchemist is transmuting with the flint from Havoc’s lighter and the transmutation circle carved into the back of his hand, and used the fire to cauterize his and Havoc’s wounds. As he fires wave after wave of hellfire at her, Roy informs Lust that if it really takes more than a normal killshot to subdue her, then he’ll just have to keep doing it until she’s gone. burn an