Isla portals back to her Wildling chambers, injured but alive. Poppy joyfully assumes Isla has succeeded in the guardians’ plan, but Isla confronts Poppy with the truth: Poppy and Terra knew Isla had power and helped Aurora. Poppy admits Aurora forced them to kill Isla’s mother and her lover so their power would pass to Isla, then raise Isla believing she was powerless and train her to seduce the Sunling king.

Isla nearly kills Poppy and considers abandoning Terra, but Isla chooses a more urgent mission. After drinking Wildling healing elixir, Isla arms herself in full armor, takes two swords, and returns to the Place of Mirrors. Isla rejects safety because Oro is innocent, trustworthy, and trapped with Grim, while Aurora must not be allowed to leave with all six stolen powers.

Back in the Place of Mirrors, Aurora’s vines and tree-made guardians attack Isla. Because Isla has spent her life fighting without magic, Isla cuts through the assault with her swords, even as Aurora mocks her for returning. Isla realizes Celeste’s betrayal hurts most because Celeste exploited Isla’s loneliness and pretended to be her sister.

As Aurora attacks, Isla concludes that the “original offense” behind the curses was not love or use of Lightlark’s heart but bloodshed: the killing of a ruler, likely the Starling ancestor. Aurora’s reaction confirms the suspicion. Aurora then shatters the ceiling with trees, cages Isla, and steals Isla’s starstick, seemingly trapping her.

Grim tells Isla to use her heart, and Isla understands that Lightlark’s heart marked her when it healed her fatal wound. Isla calls the heart from across the island, breaks the cage with renewed Wildling power, and seizes the bondmaker. When Aurora shifts into Celeste to exploit Isla’s love, Isla does not hesitate: Isla drives the bondmaker into her own palm and Celeste’s heart, killing Aurora and reclaiming power through the device.

Aurora’s death repeats the original offense, ends the Starling ruling line, and breaks the curses—but Lightlark itself fractures. Isla falls toward the island’s fiery core after Celeste’s body and the heart, unable to wield the returned power. A vine saves Isla, and Isla discovers Oro is the one using her Wildling ability, proving his love gives him access to her power. Grim realizes he cannot do the same and leaves, while Isla collapses in grief: the curses are broken, but Isla is devastated.