Guile — Constance Cooper

In the Bad Bayous the water is thick with guile, a powerful substance that wreaks unpredictable changes on objects, animals, and even people who soak too long. Sixteen-year-old orphan Yonie Watereye scrapes a living posing as someone who can sense the presence of guile, though in fact she has no such power--it's her talking cat, LaRue, who secretly performs the work.

While hunting for the secrets of her mother's past, Yonie discovers that someone is selling dangerous guile-changed objects for malicious purposes. Soon the resourceful Yonie and her feline companion face threats that could end their adventuring forever.