In an upstate New York backwater, Truly, massive from birth, has a bleak existence with her depressed father and her china doll–like sister, Serena Jane. Truly grows at an astonishing rate --- her girth the result of a pituitary gland problem --- and after her father dies when Truly is 12, Truly is sloughed off to the Dyersons, a hapless farming family. Her outsize kindness surfaces as she befriends the Dyersons' outcast daughter, Amelia, and later leaves her beloved Dyerson farm to take care of Serena Jane's husband and son after Serena Jane leaves them. Haunting the margins of Truly's story is that of Tabitha Dyerson, a rumored witch whose secrets afford a breathtaking role reversal for Truly.