Despite its provisional title, its hesitant, breath-in-the-throat half-title, Carol Shields’ Unless knows its own mind and isn’t afraid to speak it.

In this, her 10th novel, Shields constructs a tangle of questions. What is goodness? What is it worth? Is there a female goodness, distinct from the male desire for greatness? Shields gives us another writer-narrator to suggest answers – in her own life and in the lives of her characters.

Reta Winters has lost a daughter to the streets of Toronto. Norah, 19, sits at the corner of Bathurst and Bloor and begs. She carries a hand-lettered sign: “Goodness.” Winters has her own ideas about why her eldest daughter would run away from her rambling rural childhood, from her comfy philosophy-student boyfriend, from her ripening life. And readers of Shields’ novels will demand some kind of explanation. After all, her characters don’t just up and run away – even Magnus Flett in The Stone Diaries got found again, though it took decades and a trip across the globe to track him down.

Winters copes by writing “light fiction,” a clever detail that allows Shields to plot her own novel by the rules of that genre. Shields has certainly married form to content before. The labyrinthine construction of her last novel, Larry’s Party, itself the life story of a maze maker, was a clever course of subtle diversions, plot points planted like box hedges to complicate a straightforward fictional biography. But the reader may start to wonder why Shields would constrain a novel of philosophy and feminist argument? To engage critics who have levelled at Shields the charges Winters and her “light fiction” face? Shields/Winters gets revenge in the story: a journalist is humiliated; a presumptuous editor is brought to heel.

At first glance, the novel’s furnishings are classic Shields, eggshell light: Winters and her patient, painless tap-tap-tapping; the husband obligingly absent, except for long weekend walks; women friends, writers mostly, loving mostly. These are maddeningly insubtantial, as is the character of Norah, the errant daughter we never get to know. (She’s one of Shields’ gnomic good people, like the bookbinder neighbour in Larry’s Party or Brother Adam in The Box Garden.)

Shields’ tone here, however, is stinging and new. There is vicious parody (poor journalist). There is willful self-delusion. There is told-you-so vindication when the complexities of Winters’ first novel are finally appreciated. And, beneath the philosophies of goodness and evaluations of third-wave feminism, beneath even the “Ha!” sent to those who sneer at novels of domestic contentment, lies a deeper layer. Shields is reassessing a career.

How else to take the opening lines from a writer whose fiction has insisted on an unfashionable capacity for happiness: “It happens that I am going through a period of great unhappiness and loss just now.… Happiness is not what I thought.” From the start, Shields announces a more multilayered examination of her usual concerns: happiness, yes, but comfort and fidelity, too, and the freedoms of mothers and daughters, wives and ex-wives and almost-wives.

Because Shields picks her words the way I pick eggs (with firm resolve and deep caution, knowing exactly where they’ve been and what they’re capable of), I can’t shake a word association of my own. Her long, thoughtful, pang-washed sentences are “shields,” armature protecting the empty heart, the icy absence, inside each of her novels. It’s perhaps to do with living a life both academic and novelistic: Susan Sontag, Joan Givner, and sometimes even A.S. Byatt too often bury humanist heart in clever intellect.

Small Ceremonies was about a writer stealing from a writer stealing from … The novel was a box holding nothing, creativity discussed but not proven. In Swann, well, she’s always been one for unreliable narrators (and unstable tenses), but its switches between points of view were serial abandonment. The Stone Diaries held us aloof by a curious, liturgical repetition and crumbling of facts. Though there is clearly suffering in each of the novels, I just can’t come to care for such arm’s-length risks.

What’s missing from Unless is the heart to answer questions the mind can never wholly grasp. What is goodness? Whatever the answer, surely it must be felt in the body. How can we mourn for Norah when we never even see her? Unless is most likely Shields’ last novel, and so its sense of stock-taking is appropriate and understandable. Its abrupt concluding celebration, the gathering of the Winters clan, will be affirming to her many fans. But encompassing a life’s work, it also encompasses an ongoing disengagement. Looked at this way, the book’s there/not-there title rings all too true.