Daisy Collier, a reporter for her mega-church's magazine, learns that a local woman has become the oldest living American. She interviews Lucinda Spring, hoping to record her experiences and the secret of her longevity, but discovers Lucinda is an atheist who insults Daisy and her religion. Having researched Lucinda's life, Daisy surmised Lucinda exaggerated her age to collect early Social Security benefits and tries to trick her into admitting this. Instead, she finds herself entangled in a larger mystery: examining Lucinda's life to find the existential comfort that would allow a freethinker to embrace her own mortality.

The women consider the pleasures of love, of having children, and the satisfaction of a career. Lucinda insists that as important as these are, none makes up for the loss of self - of the internal voice that has guided her throughout her life. Juan, Daisy's lover, who works for Lucinda, shows up for an assignation. Lucinda discovers that Daisy thinks memories of her furtive love affair will comfort her when her time comes, and attacks the idea. Their argument leads to a volatile climax in which Lucinda realizes there is no existential comfort, but during its course, both women become tentative friends who experience and recognize the vanity of self-righteousness.