Run, By Ann Patchett

In Bel Canto, Ann Patchett's Orange Prize-winning novel, a rebel militia group silently enters the presidential residence of an unnamed South American country and courteously takes a party of diplomats and musicians hostage. Though the story is extravagantly plotted and operatically rendered, the unlikely juxtapositions within the unfolding drama prove moving almost beyond belief.

Patchett's new book similarly explores how one abrupt act can provoke sudden, miraculous shifts in human relationships, this time within a wealthy, liberal Irish-American family in snowbound Boston. The former mayor of the city, Bernard Doyle, a widower, has dragged his reluctant college-age adopted sons, Tip and Teddy, along to hear a speech by Jesse Jackson. As they leave the venue an argument erupts between Tip, the elder boy, and his father; in the swirling snow no one sees a car approach. Tip falls and breaks his ankle, but only because he is pushed out of the way by a middle-aged black woman, who is knocked unconscious. The entire event is witnessed by the woman's 11-year old daughter, Kenya.

Around 20 years earlier, Doyle and his wife Bernadette, who already had a 12-year-old son of their own, completed the family by adopting two black infant brothers. Four years later, Bernadette died of cancer. In his grief Doyle, then a successful lawyer, focused his attention on nurturing Tip and Teddy, hoping they would emulate him and run for political office. Instead, both have disappointed. Tip, searingly academic, is intent on ichthycology: he prefers fish to people. Compassionate, dreamy Teddy has also found a calling not to his father's liking – he yearns to follow Doyle's uncle, the ageing Father Sullivan, into the priesthood. Doyle has virtually given up on his natural son after a fatal car crash in which he was implicated ruined Doyle's political career.

Unbeknown to the family until this night, these events have been witnessed at a distance for years by Kenya and her mother, Tennessee. For Tip and Teddy are Tennessee's biological children. She and Kenya live close to the affluent Doyles in grittily reduced circumstances. Kenya is a talented sprinter and Girl Scout, resourceful, gazelle-like, proud and protective. Her unexpected entry into the family creates suspicion, then unconditional acceptance and healing.

In this story primarily of faith and tradition, the one element which does not convince is the emblem at its heart. A family heirloom, Bernadette's statue of the Virgin Mary, was acquired by her great-grandfather back in Ireland in order to persuade the girl he loved to marry him. It bore a likeness to that girl, and to Bernadette herself: she intended it to be passed on to the daughter she never had. To place such a potent image at the centre of the book seems clumsily literal, though other mystical references – such as Father Sullivan's unwilling ability to "heal" the sick, and Tennessee's anaesthetic-induced conversation with a dead friend who holds her most precious secret – are effortlessly presented.

The framework of the Doyles' cultured life is alluded to throughout, from the books that Doyle read to his sons as children, to Teddy's talent for reciting political rhetoric from Roosevelt to Reagan. It is, however, the reserved Tip's quoting of Thoreau to Kenya, thirsty for knowledge, which provides one of the most poignant moments of the book, which is overall a warm, generous study in humility and responsibility.