In Overlord Volume 7, Arche Eeb Rile Furt and her team, Foresight, enter Nazarick as workers, believing they can complete their mission and escape alive.
But after Ainz Ooal Gown discovers their intrusion, their fate is sealed. When Arche attempts to flee using magic, Ainz orders Shalltear Bloodfallen to teach her the terror of losing all hope of escape, then grant her a painless death.
To Ainz, this is mercy. In Nazarick, death without further suffering is considered a kindness compared to the horrors that could come before it. Yet for Arche, who desperately wants to return to her beloved younger twin sisters, this mercy comes at a devastating cost.