It's the summer of 2015, Brooklyn, and the city is sweltering from another record-breaking heat wave, this one accompanied by biblical rains. Edith, a recently retired legal librarian, and her identical twin sister, Kat, have discovered something ominous in their hall closet: it's shaped like a mushroom, it's phosphorescent, and it's rapidly consuming their wall. But that's only the beginning .

Part suspense, part screwball comedy, Jill Ciment's brilliant novel looks at what happens when our lives—so seemingly set and ordered—break down in the wake of calamity.