It is set in Fitzrovia, central London, on Saturday, 15 February 2003, as a large demonstration is taking place against the United States' 2003 invasion of Iraq.

The main character, though outwardly successful, still struggles to understand meaning in his life, exploring personal satisfaction in the post-modern, developed world.

[1][2] While researching the book, McEwan spent two years work-shadowing Neil Kitchen, a neurosurgeon at The National Hospital for Neurology and Neurosurgery in Queen Square, London.

[1][4] Saturday was also proof-read by McEwan's longstanding circle of friends who review his manuscripts, Timothy Garton Ash, Craig Raine, and Galen Strawson.

[5] McEwan's son, Greg, who like Theo played the guitar reasonably well in his youth, emphasized one difference between them, "I definitely don't wear tight black jeans".

[6] The complete novel was published by the Jonathan Cape Imprint of Random House Books in February 2005 in London, New York, and Toronto; Dutch, Hebrew, German, French, Spanish, Polish, Russian, and Japanese translations followed.

After a visit to his son's rehearsal, Perowne returns home to cook dinner, and the evening news reminds him of the grander arc of events that surround his life.

McEwan's earlier work has explored the fragility of existence using a clinical perspective,[9] Christopher Hitchens hails him a "chronicler of the physics of every-day life".

His personal contentment (at the top of his profession, and, as John Banville finds, "an unashamed beneficiary of the fruits of late capitalism"[3]) provides a hopeful side to the book, instead of the unhappiness in contemporary fiction.

[2] McEwan's previous novels highlighted the fragility of modern fulfilled life, seemingly minor incidents dramatically upsetting existence.

[10] This theme is continued in Saturday, a "tautly wound tour-de-force" set in a world where terrorism, war and politics make the news headlines, but the protagonist has to live out this life until he "collides with another fate".

[12] The characterisation of Perowne as an intelligent, self-aware man: "..a habitual observer of his own moods' [who] is given to reveries about his mental processes," allows the author to explicitly set out this theme.

"[13] Physically, Perowne is neither above nor outside the fray but at an angle to it; emotionally his own intelligence makes him apathetic, he can see both sides of the argument, and his beliefs are characterised by a series of hard choices rather than sure certainties.

[5][15] Perowne expresses a distaste for some modern literature, puzzled by, even disdaining magical realism: "What were these authors of reputation doing – grown men and women of the twentieth century – granting supernatural powers to their characters?"

Perowne earnestly tried to appreciate fiction, under instruction from his daughter he read both Anna Karenina and Madame Bovary, but could not accept their artificiality, even though they dwelt on detail and ordinariness.

In the book's climax in chapter four, while he struggles to remain calm offering medical solutions to Baxter's illness, she quotes Matthew Arnold's poem Dover Beach, which calls for civilised values in the world, temporarily placating the assailant's violent mood.

[11] As a sign of his rationalism, he appreciates the brutality of Saddam Hussein's rule as described by the Iraqi professor whom Perowne treated, at the same time taking seriously his children's concerns about the war.

[5] "Structurally, Saturday is a tightly wound tour de force of several strands"; it is both a thriller which portrays a very attractive family, and an allegory of the world after 11 September 2001 which meditates on the fragility of life.

It might resemble the Paddington crash – twisted rails, buckled, upraised commuter coaches, stretchers handed out through broken windows, the hospital's Emergency Plan in action.

[9] The protagonist's errands are surrounded by the recurring leitmotif of hyper real, ever-present screens which report the progress of the plane and the march Perowne has earlier encountered.

[5] The 26-hour narrative led critics to compare the book to similar novels, especially Ulysses by James Joyce, which features a man crossing a city,[15] and Virginia Woolf's Mrs. Dalloway, of which Michiko Kakutani described Saturday as an "up-to-the-moment, post-9/11 variation.

[5] In Literary Review, Matt Thorne wrote "this is an elegant and sophisticated novel, which is beautifully written and creates a wonderful sense of unease".

[27] Mark Lawson in The Guardian said McEwan's style had matured into "scrupulous, sensual rhythms," and noted the considered word choice that enables his work.

[14] The construction of the book was noticed by many critics; Scurr praised it, describing a series of "vivid tableaux",[9] but John Banville was less impressed, calling it an assembly of discrete set pieces, though he said the treatment of the car crash and its aftermath was "masterful", and said of Perowne's visit to his mother: "the writing is genuinely affecting in its simplicity and empathetic force.

"[3] From the initial "dramatic overture" of the aircraft scene, there were "astonishing pages of description", sometimes "heart-stopping", though it was perhaps a touch too artful at times, according to Michael Dirda in The Washington Post.

[14] Christopher Hitchens said that McEwan delivered a "virtuoso description of the aerodynamics of a squash game," enjoyable even "to a sports hater like myself",[5] Banville said he, as a literary man, had been bored by the same scene.

[3] He described Saturday as the sort of thing that a committee directed to produce a 'novel of our time' would write, the politics were "banal"; the tone arrogant, self-satisfied and incompetent; the characters cardboard cut-outs.