The Beating of a Heart Can Be Heard

While the rogue Titan keeps tearing through its own kind outside, the trainees trapped at headquarters dig up a cache of antiquated guns. Armin builds a strategy around them: a first team rides the lift down into the supply room to lure in the seven small Titans, fires into their eyes at close range, and a second team of seven drops from the rafters onto the blinded targets' napes. The risk gnaws at Armin, but Mikasa steadies him, reminding him that his thinking has pulled her and Eren through danger before. The trap is sprung and five of the seven strikes land clean; Sasha and Connie botch their cuts, and Mikasa and Annie finish the wounded Titans before anyone dies. With the room cleared, everyone refills their gas tanks.

As the group prepares to leave, Mikasa lingers at a window, watching other Titans swarm and eat the rogue that saved them, regretting that its secrets may be lost. Reiner argues for intervening, and Annie agrees that an allied Titan would be worth the risk, while Jean balks at spending lives on a monster. The debate ends when the rogue erupts from the pile, lunges at the very Titan that devoured Thomas Wagner, and crushes its nape between its teeth, using the corpse as a club against another before finally collapsing, spent.

Jean has barely repeated that a Titan can never be an ally when steam vents from the creature's neck and a human body emerges from the flesh: Eren, whole again despite the arm and leg he lost. Mikasa races down, wraps herself around him, and listens against his chest. The heartbeat she finds there undoes her; she carries him back to the rooftop and sobs over him while Armin notices the regenerated limbs and the others stare at the field of dead Titans, slowly grasping that Eren was the one who slaughtered them all.

Armin devises the eye-shot ambush that clears the seven Titans out of the supply room without maneuvering gear.

Mikasa and Annie save Sasha and Connie after their strikes fail.

The trainees resupply their gas and escape headquarters.

The rogue Titan kills the Titan that ate Thomas Wagner, then collapses from exhaustion.

Eren emerges alive from the rogue Titan's nape with his missing limbs restored, revealing to his classmates that he was the Titan.

The Beating of a Heart Can Be Heard closes volume 2 as its fifth chapter and the ninth of the series overall, by Hajime Isayama. It was published in Japan on May 9, 2010, with the English edition following on September 11, 2012, as part of the Wall Sealing arc. The anime adapts it in I Can Hear His Heartbeat: The Struggle for Trost, Part 4.

It follows Roar; the story continues in Where's the Left Arm?, alongside the special chapter Captain Levi.