Combined, the events in Carry the One could make a catalogue of tragedy. The novel begins in 1983, with five drunk and drugged-up friends accidentally killing a young girl as they drive home from a wedding in Wisconsin. What follows is 25 years chasing penance, with plenty of disappointments and a couple more deaths thrown in.

And yet the novel never buckles under its weight. The gentle panorama Carol Anshaw builds from everyday vignettes makes Carry the One feel deceptively light. The narrative glides through the lives of Alice and Nick, who were in the car, and their older sister Carmen, whose wedding they were celebrating. Saintly Carmen, pregnant and impulsively married, works in a women's shelter, campaigns for social justice and props up her siblings when they fall. Alice, obsessed with painting and with the fellow bridesmaid she slept with on the night of the accident, becomes an eventual star of the art world  and of some of the book's sexy passages. Nick, a gifted astronomer crippled by addiction, seeks escape from one in the other.

Although there is plenty of heartbreak and pain, significant events often take place in the uncharted spaces between chapters; Anshaw shows us the results of change rather than the moment itself. She glosses over drama to focus on those small, seemingly banal but powerfully revealing asides that occur in kitchens, bedrooms and cars everywhere.

Carry the One is a finely crafted novel, full of phrases you want to cut out and keep, and characters you think you know. It is delicate in its touch yet huge in its reach.

Carol Anshaw's superb Carry the One opens in 1983, with a wedding and a tragedy in quick succession. The wedding of Carmen and Matt is a pleasantly raucous affair, held outdoors at a bohemian farm in rural Wisconsin. Folk songs are loudly sung, and as a pleasant haze of alcohol and pot permeates the evening, Carmen hopes, with only a little apprehension, "to sit out this early phase of her marriage, the mortifying dances segment".

Carmen's brother and sister have both momentarily slipped away from the proceedings. Alice, to her thrilled astonishment, has been taken to a back bedroom by Matt's sister Maude and now lies underneath her, naked, being thoroughly ravished. "So far, this was the best moment of her life." Carmen and Alice's brother Nick, an extremely promising astronomer, is another floor up with new girlfriend Olivia, handing out mushrooms to the younger cousins. The evening winds down, and Nick and Olivia offer a ride to Alice and Maude. Folk singer Tom hitches along, and off they drive into the night, where they're all too stoned, drunk or preoccupied to see 10-year-old Casey Redman stray into the path of their car.

In bare description, this could sound like the opening of a particularly soapy kind of novel, but one of the many joys of Carry the One  longlisted for the Green Carnation prize  is how resolutely Anshaw refuses to indulge in cheap melodrama. Instead, she follows her characters' lives over the next 25 years, seeing them with startling clarity, an acute alertness to nuance, and no small helping of warmth and humour.

Olivia, who was driving, is arrested for Casey's death and accepts her punishment with a stoicism that shames the others. Alice, meanwhile, doesn't see Maude again for two years, before she reappears at Alice's studio. They begin an on-again, off-again affair. Carmen's marriage to Matt doesn't last, maybe because of the guilt associated with the wedding night accident or more likely because he starts an affair with the teenage babysitter. Divorced, Carmen's life becomes lonely; she marries the seemingly shallow and apolitical Rob, immediately realising that the marriage is "a small mistake", but one that nevertheless might just surprise her by making her happy.

These lives grow and mature and go off the rails and back on again through to the election of Obama in 2008. People meet and part and die and survive, just as they do in real life.

What keeps the book engrossing is Anshaw's writing. Subtle, bemused, kind and smart, she nails moment after moment: the Catholic relatives of Matt at the wedding watching Carmen as if on "an emotional safari, ready to bag a bride". Nick disguising the booze on his breath with wintergreen breath freshener, so thick it's like "talking to someone in a Norwegian forest". Carmen and Alice's loving, sisterly relationship like that of "minor diplomats, one from the arctic, the other from an equatorial nation, attempting to understand each other's customs, participate in each other's holidays".

I'd have liked more of Tom, the folk singer who earns a tainted sort of fame with a song about the tragedy, or about the siblings' parents, whose tyranny only glancingly figures in their children's lives. But these are small complaints. Carry the One is a marvellous novel, grown-up, smart and emotionally intelligent about people who, like the rest of us, try but mostly fail to keep our ducks in a row, "as if there was any reliable way of ordering ducks".

 Patrick Ness's A Monster Calls is published by Walker.