Hetty the Yeti by Dee Shulman
Hetty the Yeti lives with her parents and baby brother, Waah, in a shack on the very edge of Mythica, the Kingdom of Magical Creatures. One morning, Hetty wakes to find that something dreadful has happened. Baby Waah is sick, so Hetty must visit the wise but scary Oracle to ask for help. But the Oracle's words prove too complex for Yeti and her friends to understand. How can they unravel the cryptic clues in the Oracle's echoing chant, and solve the riddle that will explain the cure for Baby Waah's illness? This is an exciting, dramatic, life-and-death adventure set in a brilliantly atmospheric landscape.