In one of the tender reminiscences of her elder son's childhood that are scattered through this account of his destructive drug habit, Julie Myerson reveals that the young boy's word for works of fiction was "nobble". This slip of a young tongue is eloquent because this non-fiction book by a writer best known for novels - including Sleepwalking and Something Might Happen - has been accused of nobbling the privacy of her family. In turn, its hopes of being considered as a piece of writing may have been nobbled by two weeks of publicity in which various of Myerson's relatives - son, husband, sister - have been interviewed under such headlines as "Mum, What You Did Is Obscene" and "A Middle-Class Family at War."

Because the book was originally due to be published in May, and had not yet been sent out for review, almost all of the coverage was conducted by people who had not read it. Indeed, several accounts have falsely described it as a novel. Detractors may say that the central allegation against Myerson - that her hunger for a good book has made her a bad mother - can be advanced without detailed reference to the text, but I suspect that many of those who have read or written about The Lost Child will be surprised - and perhaps chastened - by its contents.

The central events are largely as reported: Julie and Jonathan Myerson become convinced that their son is addicted to skunk, a super-strength variety of cannabis. Following what the book presents as acts of theft and physical violence - combined with fears that the boy is introducing his younger siblings to drugs - the couple follow a "tough love" strategy promoted by counsellors and banish him from the family home.

The Lost Child's narrative style, though, departs starkly from the journalistic accounts. The book is filled with artistic distancing, so that the teenager is referred to only as "our son" or "the boy". And, every few pages, the account of parental hell in modern London is interrupted by a historical investigation into Mary Yelloly, an early 19th-century artist and writer who died young and whose biography Myerson was commissioned to write at the time that she began to lose her own child to addiction. These attempts to avoid the language and structure of a tabloid confessional may have been naive - in the Facebook age, a couple of finger clicks turn "the boy" into Jake Myerson - but they move the book far beyond the parody imposed on Myerson by commentators: a cold-blooded attempt to turn her son into money.

It's true that the literary quality of the work would not absolve the writer from the issues of privacy and consent, but the book includes a coda in which "the boy" meets his mother in a restaurant and comments on the manuscript, requesting changes to which she agrees. In his newspaper interviews, Jake Myerson seems to have qualified this consent to publication, so readers will simply have to decide who to trust. The book, though, cannot be accused of cruelty. Tender and gentle in its account of the child, it justifies the dedication: "He knows who he is and I love him."

Because of the media furore over the drug narrative - and also because these sections are so elementally compelling - many readers may be tempted to skip the Yelloly chapters, but they would be doing the book a disservice. As a reflection of Myerson's inability at the time of composition to write about the past without the present jumping in, the double time-structure creates powerful cross-echoes. Seeking release in research in a Norfolk graveyard, she encounters a 19th-century tombstone inscribed to an "amiable and beloved son", subtly underlining the constant, nagging connection between the two narratives: the terror that her own lost child, like his 200-year-old shadow, will also die young, still beloved though far from amiable.

Though this is structural artifice, it is also psychological honesty, and the echo-chamber approach becomes even more candid and affecting when the writer introduces a third strand: memories of the period in her teens when she was shuttled between her divorced parents' new residences. The admission of this material is again emotionally open - the book acknowledges that the boy's problems may have been connected with a spell of domestic tension in the Myerson household - and results in fascinating convergence and conversation between the storylines, as when a visit to the Yelloly home, recollections of a visit to her dad and a crisis over her son's increasing truancy are intercut across two pages.

In the end, the only crime of which Myerson is guilty is unworldliness - failing to appreciate that the blurring of news values across the media means that any story judged to have a "human interest" angle is subject to a 24-hour, cross-platform deluge of speculation, comment and blogging. The elegance and thoughtfulness of this book - and its warning of a fate that may overtake many parents - should not be lost in the extra-literary frenzy. A noble book should not be nobbled.

 Mark Lawson's novels include Going Out Live (Picador). To order The Lost Child for £13.99 with free UK p&p call Guardian book service on 0330 333 6846 or go to guardian.co.uk/bookshop