After the Betwixt Ball, Lightlark continues to deteriorate: ancient structures fall, elders die, new cracks split the Mainland, and the cursed coastal storm grows more violent. Isla and Oro have already failed to find the heart on Sky Isle and Sun Isle, so on the fifty-ninth day of the Centennial they go to Moon Isle, the last place Oro had wanted to search.

Because Oro does not want Cleo to know they are searching her isle, Oro flies Isla past the guards. Isla hates flying and clings to Oro, but their tense exchange softens when Oro adjusts his hold to make Isla feel safer. When they land, Isla notices that Moon Isle is colder than before because Oro's weakening power can no longer keep Lightlark warm or bright.

Isla and Oro cross a frozen forest where a dark-blue bird startles Isla and Oro instinctively attacks with fire. As the cold worsens, Isla struggles through the snow until Oro offers warmth and gives Isla his golden cape. Isla accepts despite her pride, and the cape restores enough heat for Isla to continue.

They reach a massive slab of ice and discover three women trapped inside: the oracles. Oro explains that an ancient king imprisoned the prophetic women so they would never leave or die; two later joined Nightshade and froze forever when Night Isle was destroyed. Oro thaws the middle oracle, confirming this site as a place where darkness meets light.

The awakened oracle recognizes Isla and Oro, says she has been warned not to help them, and hints at the many secrets between them. When Oro asks about Lightlark's heart, the oracle says it is near and confirms it is on Moon Isle, but refuses to reveal the exact location because they must find it themselves to wield it successfully.

The oracle warns Isla that lies and liars surround her and that one of the six rulers will die before the hundred days end. Before Isla can ask more, the oracle refreezes. Isla injures her knuckles pounding on the ice until Oro stops her, and the two agree to search one of the three remaining Moon Isle locations the next day, with Isla desperate to find the heart before her secret is exposed.