For the past two years Pope Francis has enchanted and bewildered the world in equal measure with his compassion and his contradictions. Expanding greatly on his acclaimed earlier book Pope Francis: Untying the Knots, Paul Vallely reexamines the complex past of Jorge Mario Bertoglio and adds nine new chapters, revealing many untold, behind-the-scenes stories from his first years in office that explain this Pope of paradoxes.

Vallely lays bare the intrigue and in-fighting surrounding Francis's attempt to cleanse the scandal-ridden Vatican Bank. He unveils the ambition and arrogance of top bureaucrats resisting the Pope's reform of the Roman Curia, as well as the hidden opposition at the highest levels that is preventing the Church from tackling the sex abuse crisis.

He explains the ambivalence of Pope Francis towards the role of women in the Church, which has frustrated American Catholic women in particular. And Vallely charts the battle lines that are being drawn between Francis and conservatives and traditionalists talking of schism in this struggle for the soul of the Catholic Church.

Consistently Francis has show a willingness to discuss issues previously considered taboo, such as the ban on those who divorce and remarry receiving Communion, his liberal instincts outraging traditionalists in the Vatican and especially in the Church hierarchy in the United States. At the same time, many of his statements have reassured conservative elements that he is not, in fact, as radical as he might appear.

Behind the icon of simplicity that Pope Francis projects is a steely and sophisticated politician who has learned from the many mistakes of his past. The Pope with the winning smile was previously a bitterly divisive figure. In his decade as leader of Argentina's Jesuits left that religious order deeply split. His behavior during Argentina's Dirty War, when military death squads snatched innocent people from the streets, raised serious questions.

Yet after a period of exile and what he has revealed as 'a time of great interior crisis' he underwent an extraordinary transformation - on which Vallely sheds new and fascinating light. The man who had been a strict conservative authoritarian was radically converted into a listening participative leader who became Bishop of the Slums, making enemies among Argentina's political classes in the process.

Charting Francis's remarkable journey to the Vatican and his first years at work there, Paul Vallely has produced a deeply nuanced and insightful portrait of perhaps the most influential person in the world today. 'Pope Francis,' he writes, 'has not just demonstrated a different way of being a pope. He has shown the world a different way of being a Catholic.'