_Radiant_ is yet another excellent installment in the League of Peoples books by James Alan Gardner, easily one of the best if not the best. I would recommend reading the other books in the series first but if one doesn't I don't believe it would be too confusing.
Unlike some of the more recent volumes, particularly _Trapped_, our heroine of the entire series, Admiral Festina Ramos, has a major starring role almost from the beginning. True to form to the other volumes however the narrator is a person that that book has introduced. Our other hero this time around is a member of the Explorer Corps as well, a woman by the name of Youn Suu from the planet Anicca, a Buddhist planet settled by people from Southeast Asia. Like other members of the Explorer Corps, her brilliant mind, a non-hazardous and non-handicapping deformity, and her lack of acceptance of society drove her into the Explorer Corps.
At the start of the book Youn Suu is serving on the Technocracy ship _Pistachio_ with her Explorer Corp partner, Tut (a remarkable and unique individual). The ship is dispatched to free a Cashling planet (the Cashling being a whiney, can-barely-do-anything-for-themselves, hedonistic species introduced earlier in the series) from the Balrog, an enigmatic, powerful alien that superficially resembles red moss but known by Festina and others to be incredibly intelligent, calculating, and powerful. The red moss has thoroughly engulfed one of the Cashling cities, a place by the name of Zoonau, leading the aliens to scream for protection from the Technocracy. Knowing that the Balrog won't knowingly harm let alone kill anyone, its massive presence is nonetheless unwelcome. The _Pistachio_ is dispatched to deal with the situation.
It soon turns out that the Balrog were basically acting as they did, when and where they did, to engineer so that both Youn Suu and Festina Ramos would be at the same place and at the same time along with the Balrog, both being needed to deal with a far greater crisis; a request to rescue colonists on the world of Muta, a world being explored and tentatively settled by the Technocracy's chief rival, the Unity. The world was once known to have been inhabited by the Fuentes (also introduced earlier in the series), a race that around the human year 4000 BC ascended to a god-like non-corporeal form, having destroyed virtually all traces of their civilization, their buildings, structures, roads, everywhere they existed. Except on Muta.
The planet attracted first one race known as the Greenstriders, a race - in a move very much out of character for the species - that sold the planet to the Unity. Something it seems had not only scared the Greenstriders into selling this world (they were otherwise never, ever known to part with land once they acquired it) but also destroyed apparently in a matter of seconds every single Unity outpost. All contact was lost and attempts to reestablish it had not been successful.
What caused their sudden disappearance (all the more remarkable when a survey from orbit reveals no physical destruction to their campsites)? Festina, Youn Suu, and Tut investigate, uncovering the answers to mysteries both ancient and modern. There is lots of action in the book, more than in some of the earlier volumes, and the mystery that unfolds in _Radiant_ ties into larger issues of the history and cosmology of the League of Peoples universe.
This I think is the arguably the best book of the series, much better than the earlier volume _Trapped_. Gardner continues to impress me as a writer and I hope that others discover him as well.