Blood Trillium by Julian May
It is now twelve years since the events recorded in Black Trillium. Haramis has devoted herself to the study of magic and science; Anigel governs her provinces with affection, seeking always the bright side of life; Kadiya has not changed - still impetuous, wild and careless. When Kadiya loses her trillium talisman in deep waters off the Windlorn Isles, the stage is set for a once peaceful world to plunge into war and catastrophe