Dina brings first-year students into Harrier's Wood to collect magically neutral snarlflowers. Abigale, Sanar, Kirol and Tam quickly fall into their familiar rhythm: caution, curiosity, teasing and practical correction. When Sanar sees a strange blue faerie, the promise of discovery pulls all four deeper into the forest.
A root trips them into a prismatic passage. They land beneath a sky with only one sun and realise Arcavios is gone. A nearby dolmen divides open daylight from perfect night, and the paintings inside show two vast beings exchanging watch over the world. At the cavern's centre sleeps the moon-crowned Isilu.
Sanar touches the elemental before his friends can stop him. Isilu wakes in terror and sends Shadowmoor pouring across the meadow. The fleeing students have not summoned an evil power; they have disturbed one half of a living balance. That distinction will take them most of the journey to understand.