The Archer's Cup (green Ember Archer Book Iii)

A Green Ember Archer story set in the midst of the buildup to the last battles for Natalia.
In this sequel to The Last Archer and The First Fowler, Jo Shanks is charged with aiding Emma on her mission to unite the secret citadels in their fight against the Preylord slavers. Alongside Cole and Heyna Blackstar, Jo and Emma must enter into the heart of a community in confusion.
Something is wrong at Blackstone Citadel. Can Jo and his friends solve the mystery and enlist Blackstone said in time to rendezvous with their allies fighting for the Mended Wood?
A citadel on the edge.
An insidious mystery to unravel.
Who will target the terror?