The Companions — Sheri S. Tepper

Three planets in deep space were named by their human discoverers to reflect their environments: lush and foreboding Jungle, which swallowed up an exploratory team; Stone, phenomenally rich in rare ore; and Moss, the most enigmatic -- and dangerous -- of the trio.

Joining her half-brother Paul, the famed linguist, on a two-person scientific expedition, Jewel Delis has come to Moss to observe the phenomenon of dancing light and to help decipher the strange musical "language" that accompanies it. But there are other mysteries alive on this exotic world covered in ever-shifting vegetation -- and something more than illuminations has enticed her away from a disastrously overpopulated homeworld to seek answers at the universe's unexplored edge. For Jewel herself is a question mark with a radical agenda that will put her at perilous odds with her planet's ruling powers -- and with the inscrutable alien races she encounters -- as she risks all for justice for the endangered beasts of the Earth.