It stars John Mills, Paola Pitagora, Stéphane Audran, Leigh Lawson, Jason Miller and Daniel Massey.

In 1958, the Catholic Church is investigating the case of a mysterious individual, Giacomo Nerone (Leigh Lawson), who is said to have performed miracles in a remote village in Southern Italy (Scontrone), before being executed by Italian Communist partisans in 1944.

The process involves a "Devil's advocate", who is tasked with discovering any details about the subject's life which would indicate that canonisation would be inappropriate.

Monsignor Blaise Meredith (John Mills) is given this responsibility, shortly after he learns he has terminal cancer.

[4] Guy Green said it had the "possibility of being a great film" but "there was a fly in the ointment by the name of Morris West.