After the Betwixt Ball disaster, Lightlark is shaken. Part of the castle lies ruined, the agora empties, and islanders fear leaving their homes. Rumors blame Grim because his earlier demonstration resembled the collapse. Cleo stops pretending to cooperate with Celeste and returns to her isle, while Oro delays his expedition with Isla to manage the wreckage and prevent noble rebellion.

On the fifty-third day, Isla and Oro climb a high wooden lattice toward a hidden hive. Isla questions Oro about the island’s heart, and Oro says it was created with concentrated energy from Lightlark’s creator, Horus Rey. When Isla mentions Cronan Malvere, Oro realizes Grim told Isla something but suggests Grim withheld more than Isla knows.

Isla is suddenly pulled into the hive and bound, but the capture is part of the plan: Isla proposed using herself as bait so Oro could gain entry. Inside, they face a pale blue, winged people and their leader, who accuses Oro of abandoning them. The leader magically holds a sword to Oro’s throat, says the island is already doomed, and cuts Oro badly while rallying the hive toward freedom through destruction.

Isla secretly frees herself and throws her dagger at the leader, but Oro stops the blade and seizes control of the situation by freezing everyone and moving the sword to the leader’s throat. Oro demands the heart’s location. The leader hints that Isla is unusual, asks for Isla to visit him after everything is over, and accepts when Isla agrees. He reveals that the heart blooms in a new place each time and chooses somewhere darkness meets light.

As Oro and Isla leave, Oro’s wound and exhaustion overwhelm him. He tries to fly them away but loses consciousness, and they crash through the trees, shielded only enough to survive. Isla realizes Oro needs water to heal and drags him to a stream, where the water slowly closes the wound through the night.

While holding Oro in the stream, Isla sees the gray-blue curse has spread across his entire left arm, explaining his weakness and Lightlark’s instability. At dawn, Isla realizes the rising sun could kill Oro before he wakes. Spotting a cave nearby, Isla pulls Oro from the water and tries to drag him into shelter.