The Rain Before It Falls, by Jonathan Coe

According to Jonathan Coe, his latest novel has been 20 years in the making. He had been waiting until he felt mature enough to do justice to the story of a blind girl and her extended family, inspired by a real event in 1987. For readers of his humorous, politically broad-canvas books such as What a Carve Up! and The Closed Circle, the result may come as a surprise, as Coe leaves behind the social comedy for something much more intimate.

When the elderly Rosamond commits suicide, it falls to her niece Gill put her things in order. At her aunt's home she finds a series of tapes Rosamond recorded just before her death for Gill to pass on to Imogen, a blind girl Gill distantly remembers from her youth. As Gill listens to the tapes, she discovers a narrative of Rosamond's life told, for Imogen's sake, through visual descriptions of photographs.

The story begins with the young Rosamond being packed off to live with her uncle and aunt on a Shropshire farm during the war. There she falls in love with her cousin Beatrice; whether this is sexual or the adoration of a lonely younger girl for a headstrong older one is not made explicit, though Rosamond does later realise that she is a lesbian. From childhood to death, the self-centredness of the women in Beatrice's family defines Rosamond's role as protector. In childhood, she is Beatrice's "blood-sister"; to Beatrice's daughter Thea she is guardian during a brief, happy period shared in London with Rosamond's partner Rebecca; and as Thea's life plays out as a tragic downward spiral, she tries to make amends for earlier mistakes with young Imogen.

Rosamond's voice is by turns sweet, regretful and nostalgic, but never bitter. It is utterly authentic and her quiet integrity makes her a compelling narrator. Though Rosamond barely talks about her own parental relationship, she transposes the mother role to Beatrice at a young age, before trying to assume it herself as Beatrice becomes more wayward. "One should never underestimate what it must feel like to know that you are not wanted by your own mother," she observes. "It is very hard to be a whole person after that." Rosamond spends the rest of her life trying to ensure that no one around her should ever feel that sense of abandonment yet despite her best efforts, feckless mothers set their daughters astray.

Coe skilfully underplays the depth of his themes and many things go unsaid, especially around the subject of lesbianism (as perhaps befits an elderly lady of a certain era). The gaps between periods of time as he moves between photographs create an ebb and flow of hopes and ambitions abandoned or compromised. Coe leaves us to consider whether destiny is behind the recurrence of random events or inherited faults. The final image in the book, which repeats a key moment of distress in Rosamond and Beatrice's childhood, is so simple and yet so expressive at achieving this sad confusion that it brought tears to my eyes.

The double distancing effect of a narrative told from beyond the grave and as a visual description of photos is ingenious – he perfectly captures that slight shudder of one's world when looking at one's eldest relatives as children and the unavoidable reading of later sins into their child's features. Unlike the multi-strand storytelling of many of Coe's past books such as The House of Sleep or The Rotters' Club, this device keeps him tethered to a chronological structure and a single character. The result is like every conversation you wished you'd had with an older relative before they were gone.

The intervening years have made Coe a writer of extraordinary maturity, warmth and subtlety. This is an impeccable character study and a vivid evocation of time and place. As a novelist, he has just produced his best work.

Viking, £17.99