One of my very favorite books. I've read it many times.
The survey team on a recently discovered planet are in trouble, in several ways. Many of them are at odds with each other, the planet is dangerous, they cannot prove the sentience of an obviously intelligent native race because they can't determine if they have language, and now one of the survey team has been murdered. Tocohl Susumo is sent to the planet to assist the team. She is a Hellspark, one of a race of polyglot traders. Understanding that language is a great deal more than just speech, she is able to diagnose some of their problems immediately, but deciphering the language of the native Sprookjes and finding the killer among the team members are a little more difficult ... but very urgent.
I'm not sure why I return to this book again and again. I often reread it when I need a lift. It just makes me feel good.