Sister Agatha is an extern nun in the cloistered order at the Our Lady of Hope Monastery near a small New Mexican desert town. As such, Sister Agatha is the link between her cloistered sisters and the outside world. Usually this means running errands in the monastery's slowly dying car (dubbed the Anti-Chrystler) or their motorcycle, with Pax, the order's German Shepard, in the side car. But sometimes it means something a bit more — like now when the diocese is upset by reports of a young girl whose parents claim is receiving visitations from the Virgin Mary and providing insight into future events.
Wanting neither to ignore a real miracle, nor give credence to what might be merely an attempt to defraud the faithful, they ask Sister Agatha to investigate. But her inquires are soon complicated when the girl herself disappears, apparently having been kidnapped, and Sister Agatha will need more than faith to bring her home.