Seventeen-year-old Cassie Brittman is looking forward to her violin recital and the prom-until the hospital calls and she learns that her grandfather, noted mystical painter Daniel Brittman, is dying. Cassie, her mother, Anne, and Anne's new boyfriend travel to the family farm and immediately see that things are far from normal. The farm, including Great-Grandmother Hannah's spiral garden, is almost destroyed, and someone (or something) seems to be stalking them. Cassie soon finds herself at the center of an age-old battle between two supernatural clans-the sinister, dark Red Clan and her own family, the Green Clan. For it turns out that Cassie's grandfather is half nature spirit, half human. . . .