This is a great second book in the Galactic Milieu trilogy, & plots the path of Dorothea Macdonald, a young girl, very affected by the metapsychic gifts she is born with.
She loses her Mother, Aunt, and Uncle, at a young age - all victims of Hydra, and Fury, those metapsychic killers so closely associated with the Remillard family.
Because of this she, and her older brother, Kenneth, go to live with their father, an airplant farmer on the Scottish planet, Caledonia, whose mental latency helped contribute to his divorce from Dorothea's mother.
Dorothea loves her father and, even at the early age of five, knows that the only reason she and Kenneth were allowed to live with him, is because they, too, are tested as latent so, when Dorothea's gifts start slowly being released, it's only because she's so strong in them all, that she's able to hide them.
While growing up on the farm, she's contacted by the youngest son of the Remillard family, Jack, known as the Bodiless, who is as strong in his metapsychic elements as she is, so he wants to be friends with someone he feels will know how life is like for such strong meta powers.
Unfortunately, because she is trying to hide her powers, she assumes that Jack is trying to trick her into showing them, and so she blocks him, thinking him a part of the Hydra/Fury mix.
Eventually, Dorothea can't hide what she is, and so is collected from Caledonia, by her Talented grandmother, to go live on Earth, to be trained in her Talents.
While Dorothea grows, she learns to watch and listen to those around her, as those Rebels who are against joining up with the Galactic Milieu, with its mysterious Lylmik, and it's four client races.
The politics of the Human Race joining with the five races in Unity, is something that she learns isn't popular with not only the Latent humans, but also a growing group of those who are high in their mental talents.
Hydra/Fury, consider Dorothea, and Jack, to be their greatest enemies, and plot to kill them, only to be weakened when they attack Dorothea further and, with the secret help of Jack, Dorothea kills one of the Hydra, leaving them in hiding.
Dorothea slowly learns to trust Jack, and its only when Jack, and his brother, Marc, helps her to save her beloved planet, Caledonia - an action that nearly kills her in the process, and which earns her the name of Diamond Mask - that Dorothea realises that Jack loves her.
All throughout this book, I was in two minds over the Unity thing, as I felt a great sympathy for the Rebel cause, but also understood the politics involved in the five race's worry about humanity joining with them, not only as a race much stronger in the Talents than all but the Lylmik , but also the fact that we're an argumentative lot, and Unity is all about peace!
I did enjoy this more than the first book, as there was a bit too much talk of religion in that. This nook, on the other hand, gives a much better insight into Humanity's political problems, and how the five races look on them, because of it.
There was a great ending to it, too, which makes me anxious to start the third book in the trilogy: Magnificat!