The Toll (Arc of a Scythe #3) by Neal Shusterman
It’s been three years since Rowan and Citra disappeared; since Scythe Goddard came into power; since the Thunderhead closed itself off to everyone but Grayson Tolliver.
In this pulse-pounding conclusion to New York Times bestselling author Neal Shusterman’s Arc of a Scythe trilogy, constitutions are tested and old friends are brought back from the dead.-Goodreads