Isla wakes after Cleo’s trial feeling dangerously cold and weak. Ella tends to her with fire, tea, broth, and baths, but by night Isla has only slightly recovered. Celeste visits with Starling soup and offers to go to Moon Isle in Isla’s place, but Isla refuses because the full moon provides their only chance to reach the Moonling library undiscovered, and Celeste cannot move through danger as Isla can.

That night, Juniper’s information proves correct: the bridge to Moon Isle is unguarded because the Moonling curse makes the sea hunt Moonling blood during every full moon. Isla disguises herself with white hair and the right clothing, then crosses into the empty, ice-bright isle while the sea violently batters the cliffs. Because no Moonling would survive outside the palace during the full moon, Isla knows being seen outdoors would expose her immediately.

Unable to use the exposed path to the castle entrance, Isla circles the rock and spots an unbarred window high above. Despite her injured arm, feverish weakness, and the cold in her chest, Isla begins climbing the nearly flat cliff, relying on Terra’s old training to move by instinct rather than fear. When a rock hold breaks and Isla falls, she uses the hidden blade in her choker necklace to stop herself long enough to find new handholds.

Isla reaches the window, slips inside, and enters Cleo’s silent marble castle. She searches deeper for the library, which Celeste learned lies at the back of the palace overlooking the sea. As Isla moves through the labyrinthine corridors, Isla notices far more guards than she has seen elsewhere and hears signs of water being wielded and frozen, making Isla wonder what Cleo is preparing.

When Isla sees a flash of white, Isla hides in an empty room. Two Moonling guards approach, one saying he saw someone and the other questioning how anyone could get past the legion. Isla realizes Cleo appears to be building an army, but before Isla can understand why, the door to Isla’s hiding place flies open.