Archbishop D'Este plans to use The Silent Noise, a destructive sound-wave device, to destroy Rome. Lady Caterina is held under house arrest for her suspicions, and is secretly brought before D'Este so that he may try to persuade her to join his cause, and to join forces with the Contra Mundi.
Abel, still distraught over the loss of Sister Noelle, receives word from Sister Esther that Caterina is in trouble, and arrives in time to save her from D'Este, only to discover that it is actually Isaak Fernand von Kampfer, a high ranking official of the Contra Mundi, a part of the Rosen Creuz Orden, in disguise.
Meanwhile, the remaining AX members discover where the Silent Noise is, and when they arrive they meet the real D'Este. The members, Father Wordsworth, Father Tres, Father Leon, Father Havel, and Father Hugue all try to take it out and reach D'Este, as he beings to play it!
Elsewhere, Abel goes 40% and battles Kampfer. After taking considerable damage and running out of time. Abel goes 80% and easily overpowers Kampfer. He asks Kampfer how to stop the Silent Noise, which has begun to play. Kampfer tells him that he must destroy the main control, which is inside his body. Abel tries to kill Kampfer, but cannot bring himself to do it and thus cannot violate his oath never to kill again.
The AX members manage to stop the noise and capture D'Este. Kampfer flees, leaving a wounded Abel.