The is the final book in the series that began with The Cold Minds, in a universe where humanity has had to flee Earth after it was taken over in an alien invasion. They found refuge in the Hidden Worlds, but in the last book, the Cold Minds have found them there.
Also in the last book, they’ve realized that the Cold Minds ships are piloted by humans, and these humans clearly were once free. Linnea and Iain decide to make a jump back to Earth to see if they can find these people.
What they find is two groups of people living around Neptune and the other outer worlds of the solar system, always keeping one step ahead of the Cold Minds on Earth. There’s tension there, and Linnea and Iain must figure out their secrets, and how they’ve managed to survive near Earth so long.
This was a good end to the series. A few questions were answered, and a decent ending was achieved. I’ll admit I’d have liked to have seen a little bit more of some events that the ending hints at, but I’m overall satisfied with the series.