When twelve-year-old Gus LeGarde and his two best friends, Elsbeth and Siegfried, stumble on a hermit’s cabin in the woods in the summer of 1965, they’re unprepared for Tully, the crotchety old man who sticks his head out the window and threatens to shoot them. But more surprising is Tully’s best friend, a young Indian girl spirit, Penaki, who reveals herself to the children by forming patterns with butterflies, rattling tin cups, drawing on dusty mirrors, and flipping book pages.