Tess and Matt have reached the final part of their journey. All that remains is taking down the Great Council and stopping the Grounders once and for all. But after a horrible revelation that's shattered everything, Tess isn't sure if it's even moral to continue on the mission - and she isn't sure who she even is anymore. But when the full horror of the Grounders' plan for humanity is revealed to Tess and Matt, they will have no choice but to continue the war and risk their lives to bring down the Great Council. Also, Tess learns that her mother was hiding a secret about the Grounders, a secret that could decide the fate of Earth.