The decades-long conflict with the Wardens, the genocidal faction of alien Echoes that started the war on Earth in 2069, rages on. Dani, an Echo, fights alongside humans and other aliens against the Wardens. As the bond of her newfound family strengthens, she continues to struggle to find a viable solution to retake Boston from the Wardens. Maine's civilian and Commonwealth military alliance against the enemy remains intact, but Dani's relationship with Colonel Houston becomes more strained with rogue Warden attacks, unreliable intelligence reports, and the high casualty counts that will come when they move on the enemy stronghold in the city. Rowan's unwavering ambition to eliminate all humans from Earth, rise within Warden ranks, and capture Dani drives him to commit treason. When Dani learns that Rowan is behind an assault in Maine that wounds and kills several people on the Commonwealth base, her well-orchestrated plan against Boston is replaced with one focused only on rescue ... and revenge.