An 11-year-old girl named Anna O'Donnell, a deeply religious and energetic child believes that she is living off manna (in the Bible, an edible substance given by God to the Israelites during their long journey in the desert) from heaven. Anna's parents claim that their daughter can live without food, but things are not as they seem. Anna claims that she has not had food for over four months, and a small group in the town has formed to determine if the girl's claims are true.
As a result, a journalist named Nurse Lib Wright (a veteran of the Crimean campaign in 1854) is dispatched to observe the aforementioned Anna O'Donnell in her natural environment. There, Lib and another nurse alternate eight hours of watching the girl to ensure she does not eat. Lib quickly discovers that Anna's parents are scam artists. They have put out a tip jar so that people could witness Anna's "miracle." Lib is not fazed by their behavior, however, and is resigned to finding out more about Anna and her supposed "miracle." To that end, she scours Anna's room for food and begins to restrict visitation, including of some other medical professionals.
Other journalists soon flock to see Anna, but they cannot see her. At the same time, Anna tells Lib about her brother who had died suddenly (and much to Anna's chagrin, without giving communion) nine months before her arrival. Lib finally begins to trust the aforementioned journalist and allows him to meet with Anna, who he sees is wasting away. Lib very quickly acts and tries to get Anna to eat to no avail. Shortly thereafter, Lib discovers that Anna's mother has been secretly feeding her food at night during their "kiss." But Anna now refuses to eat the food, which she thought was Manna. Shortly after that, Lib determines that she is fasting in hopes of resurrecting her brother. Close to death, Lib kidnaps Anna and whisks her away to Australia in a desperate bid to save her life. Ultimately, after burning down Anna's parent’s home, they escape, and Lib and the journalist get married.
