The Prayers of Agnes Sparrow is the story of an unusual woman, Agnes Sparrow. No longer able or willing to leave her home, where she is cared for by her long-suffering sister Griselda, Agnes has committed her life to the one thing she can do - besides eat. Agnes Sparrow prays, and when Agnes prays, things happen, including major miracles of the cancer- and ulcer-healing variety, along with various minor miracles, not the least of which are the recovery of lost objects and a prize-winning pumpkin. The rural residents of Bright's Pond are so enamored with Agnes they plan to have a sign erected on the interstate that reads, "Welcome to Bright's Pond, Home of Agnes Sparrow". This is something Agnes doesn't want and sends Griselda to fight city hall.

Griselda's petitions are shot down and the sign plans press forward until a stranger comes to town looking for his miracle from Agnes. The truth of Agnes's odd motivation comes out when the town reels after the murder of a beloved community member. How could Agnes allow such evil in their midst? Didn't she know? Well, the prayers of Agnes Sparrow have more to do with Agnes than God. Agnes has been praying to atone for a sin committed when she was a child. After some tense days, the townsfolk, Griselda, and Agnes decide they all need to find their way back to the true source of the miracles - God.