Ian McEwan, master of obsession, fumbles with his latest, The Children Act

Adam Henry, the precocious 17-year-old Jehovah's Witness at the centre of Ian McEwan's 14th novel, is in dire need of a life-saving blood transfusion. But he's not the only one. The Children Act could also do with a few bags of that essential fluid – platelets, red and white cells, and all.

How one of the English-speaking world's most engaging and accomplished novelists (The Cement Garden, The Child in Time, Amsterdam, Atonement, and Solar, just to name personal favourites) could, or would, write such a lifeless book is a bit of a head-scratcher, although not entirely.

Fiona Maye, the late-middle-aged High Court judge protagonist of The Children Act, has much in common with late-middle-aged Henry Perowne, the neurosurgeon hero of McEwan's 2005 novel Saturday. They share a high IQ and low EQ, demanding jobs that have life-and-death implications for those they deal with on a daily basis, and are essentially bloodless and privileged creatures shaken out of their British upper-class complacency by an encounter with a person of unrepressed anger and vitality.

Saturday, almost universally praised, is a book I found smug, as well as somewhat pretentious in its obvious striving for profundity – all craft and control. The Children Act is much the same, although not even as fluidly written and complexly executed.

The Children Act, like its heroine, is cerebral rather than smart, overly determined, and holds the reader at a distance.

All work and no play make Fiona a dull gal (her disaffected husband Jack says she's "lost the art of play"). But here's the conundrum: how do you write about a dull person, especially when sticking to a close third-person POV, and not write a dull book?

Fiona's marriage is sexless (Jack has been counting: it's been seven weeks and a day as the novel begins). Childless, through attrition, she rose in her profession until she stood proudly before her bewigged colleagues in her robes and "she knew the game was up, she belonged to the law as some women had once been brides of Christ." (The too-obvious irony here is that she's a family court judge deciding the fates of children when she has no children herself.) She's an accomplished classical pianist who can't play jazz because she has too much respect for "the rules."

It's breaking an unspoken rule that launches Fiona into thinking with her heart rather than her head, albeit only for a short, dizzying time, and it's a beautiful extended scene. In the midst of hearing a case in which a hospital is petitioning to be allowed to give a blood transfusion to Adam against his own and his parents' religious objections, Fiona heads to the hospital to talk with the young Jehovah's Witness himself.

McEwan can ratchet up tension, an unnameable and yet tangible feeling of dread, like almost no one else, and just over halfway through The Children Act it begins to seem as if the master of obsession is going to do his thing. But the author doggedly stays the course with the mistress of self-denial, Fiona Maye, who wears the law like a horsehair shirt.

The Children Act made me want to shout, "Will one of the real Ian McEwans please stand up!" – for his guises are many and delightful.

There's McEwan the satirist (the Booker-winning Amsterdam, Solar, and the darker, less antic, The Child in Time.) There's McEwan the creep-meister of obsession and contemporary gothic (The Cement Garden, The Comfort of Strangers, Enduring Love). And there's McEwan the thrilling historical novelist (Black Dogs and Atonement).

New Yorker critic James Wood has explained that his problem with McEwan, a writer he does admire, is that the novelist is too fond of narrative manipulation and with the creation of a thriller-like effect. That narrative manipulation is all too evident here, minus the thriller-like effect.

Adam Henry captivates the reader as much as he captivates Fiona, his nurses, and pretty much anyone who comes into contact with him. He's a vital, beautiful, uncanny, and confused boy (as all teenage boys are through the eyes of those who love them) who, with his life force draining, brings life into the novel. Unfortunately, he doesn't appear until exactly 102 pages into a 226-page book. In journalism this would be called "burying the lead;" in fiction there ought to be a term for it. Maybe something legal and Latinate for "losing your reader"?

Zsuzsi Gartner is the author of the Giller-shortlisted Better Living through Plastic Explosives and editor of Darwin's Bastards: Astounding Tales from Tomorrow.