The decades-long conflict with the Wardens, the genocidal faction of alien Echoes that started the war on Earth, rages on. Dani, an Echo, fights alongside humans and other aliens against them. Maine’s civilian and Commonwealth military alliance against the enemy remains intact, but Dani’s relationship with Colonel Houston becomes more strained. When one Warden makes an attack personal and aimed at Dani, her retaliation becomes focused on rescue and revenge.