Historian and haematologist Dr Duffin diagnosed severe acute leukaemia from a bone marrow sample. Surprisingly the patient survived, following prayers to a woman 200 years previously who had become Canada's first Catholic saint.

This led Duffin to explore the Vatican Secret Archives. Four purported miracles must lie behind every 'saint', but unlike Lourdes, Vatican records are shielded from public scrutiny. Indeed all details of Vatican healings since 1939 are 'sealed'. She was, however, able to examine papers from 1588 until 1939, covering 1,400 'miracles'. As the revolution in diagnostic imaging is only 40 years old, her study reveals the history of medicine, but little in the way of hard science.

In fact, she persistently fails to ask the hard questions. Was she being gullible to believe these stories? What happens to those who stop medication? Why are these stories so different from the Gospel miracles (which she ignores)? Neither does she apply any rigour in asking what might constitute a miracle.

So she notes (without comment) that her leukaemia patient also received 'aggressive chemotherapy'. Then wherein lies the miracle – or the saint?