The domed city of Evanescence has been overrun with renegade androids and the disfavored from The Waste. Ellani Drexel joins Guster and a small band of refugees in escaping the city through the Undertunnel. They hope to make it to Cadence, their sister city, but once the door has been sealed behind them, they find that the dark, days-long journey through the tunnel is more difficult than it appears. Tensions grow high as reality sets in and truths are revealed. Ella already knows some of it--like her involvement in her city's downfall and her determination to not only make it up to the survivors, but to one day reclaim her home. But she doesn't know why Guster is suddenly acting strange. And she isn't counting on the game-changing secret that Quentin reveals about Guster. Nor does she know that the Disfavored are after her. And she certainly doesn't know that the Anansi Virus that she planted in Nexis had a secondary protocol... It's called Redux. And it's waiting for Ella.