While her friends are spending their summers having pool parties and sleepovers, twelve-year-old Carol is spending hers in the middle of the New Mexico desert, helping her parents move the grandfather she's never met into a home for people with dementia. At first, Carol avoids prickly Grandpa Serge. But as the summer wears on and the heat bears down, Carol finds herself drawn to him, fascinated by the crazy stories he tells her about a healing tree, a green-glass lake, and the bees that will bring back the rain and end a hundred years of drought.