The Silent Island

Guided by a mysterious message, Cori, Tarn and Jem sail north to meet the secretive Loyalists, who will help them on their quest for the Oceanforged Armour.
Instead, the Loyalists warn of a looming disaster. Unless Cori can master all the powers of the Champions before it strikes, Aquinta will be doomed.
The Loyalists believe that a piece of armour may be hidden in Mutemount. But sea monsters once lurked in those waters, and no one who has travelled near the silent island in the last century has ever returned…