Sister Molly Keaton is caught between the madhouse and the jailhouse. Its a strange position for a novice in the Order of the Sisters of Mercy. But the strangest thing of all is the cause of her dilemma. Sister Molly is being visited by the Virgin Mary, and that sainted lady has told her to give one last message to the world or humanity will suffer the consequences of her failure.

A nurse at St. Johns Hospital in New York City, Sister Molly is the target of a homicide investigation led by Detective Tom Long. Tom has lost his wife to a heart attack she shouldnt have had and his faith to the injustice of his deeply religious and loving wifes death. Karen Long died at St. Johns, and too many other anomalous deaths have occurred. For Tom, Sister Molly is the prime suspect in a serial murder case, and he doesnt believe a word she says about visions and messages.

Ave Maria traces the journey of these two seemingly very different people as they struggle with the evidence of crime and miracle, their own anguish and doubt and, ultimately, their role in the fate of the world. Brought together by the forces of evil, they must rediscover faith in the good.