In Ann Patchett’s novels, the most bruising form of love is parental, whether or not the parent concerned has a biological connection with the child whom he or she adores. In one of her loveliest books, The Patron Saint of Liars, a thoroughly decent man declares his fatherly feelings for Sissy, his lover’s small daughter: “I had lived through losing a woman before and if it happened I could live through it again. It was Sissy I flatly could not do without.” Adoption loomed large in that novel and does so again in Run.

Bernard Doyle, a 63-year-old disgraced Boston politician, clings mawkishly to his adopted black sons, Tip and Teddy, trying to mould them into the shape of the do-gooder that he once was. The boys, in their early twenties, do as they’re told, attending lectures (the book opens with them trudging unwillingly to hear Jesse Jackson), but their hearts are elsewhere. Tip lives for ichthyology, the categorising of dead fish in the warm silence of a Harvard lab affecting him more passionately than Jackson’s call to leadership. Teddy, always referred to as “the sweet one”, has the knack of total recall: he is word-perfect on every political harangue he has been forced to listen to.

But this is just a party trick; what involves him is the Catholic church, particularly his mother’s 88-year-old uncle, a priest now residing in a nursing home where he has the unenviable reputation of being able to cure the sick. Teddy’s near-worship of the man is mixed up with his love for Bernadette (the mother he can hardly remember, who died soon after adopting the boys) and for what Doyle calls Teddy’s “dreamy infatuation” with her religion.

If the boys are disappointments to their father, they are redeemed by their compliance. Sullivan, Doyle’s natural son, is without this saving grace. Having resisted his father’s sanitised curriculum, he has become the family’s needling and ironic bad boy, the scandalous cause of Doyle’s political downfall. Outside the clammy circle of love constructed by Doyle, Teddy and Tip, Sullivan rarely visits Doyle’s house in a snooty part of Boston, and it’s pure coincidence that he is at home when the drama at the centre of the novel takes place: Tip is pushed clear of an oncoming car on an icy road by a black woman who, in saving him, is badly injured. It transpires that this woman and her young daughter, Kenya, have been keeping watchful, fascinated eyes on the Doyles for a long time. Once again, Doyle and his sons, who have never recovered from Bernadette’s death, have to deal with a jolting change in their lives, as does Kenya, an intelligent, wary child and a superlative runner, whose carefully worked-out adaptation to life on the right side of the tracks is one of the book’s many joys.

The story could have become mawkish; there’s rather a lot of soupy goodness and dull virtue. But there’s no chance of that as long as Sullivan is there to observe the scene, spreading his snarky sarcasm around like dollops of cold glitter, as chilling as the New England winter that trips up the characters in more ways than one. This entertaining black sheep, who holds tragedy up to ridicule, is one of the most mesmerising characters that Patchett, the most compassionate of novelists, has created.

RUN by Ann Patchett
Bloomsbury £14.99 pp295
Buy the book here at the offer price of £13.49 (inc p&p)

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