Isla decides she cannot accept Oro’s plan to end the curses if it means killing Grim. She goes to Celeste and asks for forgiveness before proposing a desperate alternative: Celeste will steal the bondbreaker from Oro’s secret library, and Isla, Celeste, and Grim will split its blood cost so their curses can be broken without Grim dying. Isla chooses the Place of Mirrors because Oro’s powers will not work there, then returns to her room, leaves Oro a letter, and refuses to steal Lightlark’s heart because doing so would doom the island.

After Celeste creates a distraction in the palace, Isla summons Grim and tells him Oro means to kill him. Grim agrees instantly to help Isla save her realm, but when he portals them to Wild Isle, the ancient Wildling forest nullifies his Nightshade curse and lets him stand under the night sky. Before they reach the Place of Mirrors, Grim confesses that Isla’s sensual dreams are actually memories: Isla visited him in Nightshade lands before the Centennial, they fell in love, and Grim erased all memories involving him.

Shaken and unable to trust Grim, Isla runs through the Wildling forest to the Place of Mirrors, where the trees close behind her as if protecting her. She finds Celeste holding the supposed bondbreaker, a golden glass needle. When Isla and Celeste pierce their palms, Grim tries to stop them, but the device transfers something from Isla to Celeste instead of taking blood.

Celeste reveals herself as a traitor. The needle is not a bondbreaker but a bondmaker, an enchanted device that transfers abilities. Because Oro and Grim have both fallen in love with Isla, their powers are accessible through her, and Celeste drains them all at once. Oro arrives and is weakened alongside Grim, while Celeste’s blood displays the powers of all six realms.

Celeste then transforms and reveals she is Aurora, the ancient Starling ruler believed to have died when the curses were cast. Aurora explains that she faked her death, caused the curses in revenge after King Egan loved Isla’s ancestor Violet instead of her, and spent centuries taking new Starling identities while waiting to seize all six realms’ powers. Aurora also reveals Isla is both Wildling and Nightshade, born from a Wildling and one of Grim’s powerful generals, and that Grim became Aurora’s accomplice after learning her identity because he believed the plan would save his realm, Isla’s realm, and their future together.

Isla understands that Aurora has manipulated the entire Centennial, killed Juniper, likely attacked Azul through her schemes, and used Isla as the central piece in a larger game. Isla tries to kill Aurora with the serpent dagger from the Starling shop, but Aurora had planted and enchanted it so it could not harm her. Aurora shatters the Place of Mirrors with Wildling vines and prepares to kill Isla, Oro, and Grim, but Isla secretly kept her starstick and escapes through a puddle of stars.