The narrator awakens chained to a cot in the cinder-block jailhouse of Uz, Nebraska, on what will come to be called Black Sunday. She is disoriented and feels terrifyingly weightless, as if something vital has been drained from her. A massive dust storm howls outside, choking the cell with heat and dirt; the sky darkens until she mistakes afternoon for midnight. The Sheriff's house across the property fades from view as the black blizzard engulfs the town.

The Sheriff's unnamed tabby cat appears briefly on her chest, then leaps through the bars into the storm. The cat triggers a memory of the Sheriff drowning the cat's litter of kittens within earshot of the narrator's cell, demonstrating his casual cruelty. As her senses return, the narrator recovers her identity: she is the Antidote, a prairie witch who works in Room 11 of a boardinghouse, advertised as a banker of memories. For fifteen years she has absorbed customers' unwanted memories during trance-states, storing them in her body in exchange for payment.

She realizes with horror that during the storm—or her sleep—every deposit she held has been siphoned away. Fifteen years of townspeople's banked secrets, sins, and griefs are simply gone, leaving her bankrupt. Her customers, themselves losing harvests and farms to the dust, will eventually come to withdraw memories she can no longer return. Her meticulous ledgers record transactions but not the contents of what she held.

Amid this devastation, the narrator addresses an unseen "You"—her son. She recalls being a fifteen-year-old fugitive from the Milford Home for Unwed Mothers, where she gave birth and briefly nursed him before nurses, she believes, drugged her and falsely declared the baby dead. Clinging to the conviction that he is alive, she finds the will to sit up and keep living, pledging continued survival for the chance of reunion.