Should people write about actual events, in the first person, if they are not Irish, or over 70?

David Eggers, just 29 and of good mid-Western stock, throws the question into the long, guitar-riffing preface to this book, then answers it with such an engaging, energetic, self-conscious and, yes, heartbreaking memoir that he has been on the bestseller lists for months in the United States, and is being hailed as a new star in that country’s literary firmament.

At 21, and within the space of 32 days, Eggers lost both his parents to cancer and was left to bring up his eight-year-old brother, Toph (pronounced Tofe, and short for Christopher). This sent a geological rift through his life, fracturing continuity and pushing together things which are normally apart. It is out of these uneasy disjunctions that Eggers has conjured a compelling, personal story which also has plenty to say about what it means to be young and eager, and trying to carve out a decent life in the US today.

Eggers sold the family’s suburban house in Chicago and headed for California, where his older brother, Bill, was working, and his older sister, Beth, was in law school. He rented a house, found a school for Toph, and began working with friends to get an iconoclastic new magazine, Might, off the ground.

But the hip, media-savvy 20-something goes home to be a surrogate parent, endlessly fretting that if he gets it wrong Toph will grow up “with an interest in guns and uniforms”. The enthusiastic Frisbee player lives a life overshadowed by loss; the squalid ex-college kid who has “not yet grasped the difference between paper mess and food mess” is driven to deliver “The State of the Family Room Address”, lest the authorities take Toph away “to where the laundry is done properly and frequently, where the parental figures can cook and do so regularly, where there is no running around the house poking each other with sticks from the backyard”.

Eggers is a daring writer, layering ironies, endlessly deconstructing, understanding in every corpuscle of his being that in today’s world nothing is ever what it seems, but also “fodder”, to be looped back endlessly through the films and television programmes we feed on until they themselves become as much part of our reality as the events they grow out of.

Paranoid fantasies stalk his thoughts. His brother and his friends become characters who leap out of character to harangue him for his pretension and self-delusion. A television interviewer turns therapist, and is then berated for being nothing more than a cheap device, allowing Eggers to set down the stories of his earlier life.

But he can write it straight as well. In his hands you are spared nothing, not one fleck of blood or blob of bile, of his mother’s last days, spitting up green slime into a half-moon cup held beneath her lip. He tells you of his father’s sly alcoholism - of AA meetings held at home while he continued to drink - and his friends’ assorted weaknesses and ctastrophes. He takes you up and down the streets of San Francisco, sharing his delight in it all, the hills and the trams, then later leads you with him on his disenchantment with the city. “I’m getting sick of the hills, always the hills, the turning the wheels to park, and the street cleaning and those fucking buses attached to the ropes or wires or whatever.”

Under his youthful eye the perils of modern parenthood are viewed afresh: the awfulness of the liberal, dope-condoning mothers at the school gate; the angry eyes of the homeroom teacher; the terror of leaving a child with an unknown babysitter who might do dreadful things with Vaseline and paint thinner. “I will come and the door will be open, wide. The babysitter will be gone and there will be silence.”

Then the focus shifts and you are plunged into his daytime world of friends with names like Moodie and Zev, and their fragile media dreams. “We seek out alliances with others, like us, who are taking a formless and mute mass of human potential and are attempting to make it speak, sing, scream, to mold it into a political force. Or at least use it to get themselves in Time and Newsweek.”

Then the two bump and blur. Eggers goes to an open-house event at Toph’s school. They arrive late, both wrongly dressed (“Look at your buttons. They’re off. Retard.”), Eggers hoping to pull (“My goal...was to meet an attractive single mother and have Toph befriend the mother’s son so we can arrange playdates, during which the mother and I will go upstairs and screw around while the kids play outside...”), while Toph prays, “Please, don’t. Please.”

AHWOSG (as Eggers calls it) is fast and funny. Its dialogue springs off the page, and it can take you anywhere, from the waiting area at a hospital emergency room to the bitter cold of Lake Michigan in winter, in just a few deft sentences. It can also irritate, tipping over at times into a too-slick knowingness or indulgent self-absorption. But the love that shines out of it - daily, exasperating, dutiful, non-negotiable love - lifts it above such dangerous swamps.

The writer’s relationship with his young brother is a living, breathing bond, even though Toph’s baseball cap smells of urine and Eggers worries constantly that when they are seen together he, the older one, will be perceived as a child molester.

They fight and play and argue. Eggers coaches Toph at baseball, cuts his hair, rubs his back at night and worries about his relationships with girls. He understands, with a maturity well beyond his years, that it is Toph’s life that shapes his own and gives it meaning. And in the love he shows for his brother, the love he remembers from his own parents, most particularly his mother, is clearly passed on down the family line.

But this is not a sentimental book. Eggers is there before you, telling you in the preface what he’s up to, and how he’s going to make you feel. It’s the endearing narrator, he says, that’ll get to you, and the brotherly love. And, irritatingly, of course, he’s exactly right.

HILARY WILCE