Chris Cleave begins his fourth novel, “Everyone Brave is Forgiven,” with a moment of pluckiness: It’s September 1939, and 18-year-old Mary North, a daughter of privilege, has left school to return to London, where she means to take part in the war. “She did it at lunch,” Cleave writes, “in case her mother said no. . . . Nineteen hours later she reached St. Pancras, in clouds of steam, still wearing her alpine sweater. The train’s whistle screamed. London, then. It was a city in love with beginnings.”

Think of those sentences, like many openings, as a litmus test for the narrative that follows: a little breathless, built of broad strokes, in which the inevitable losses and depredations of World War II are presented, more or less, through a social filter, as a mechanism for the vagaries of love.

This makes sense, to some extent, since Cleave was inspired by the saga of his grandparents, who got engaged in 1941 and then didn’t see each other again for three years. Still, despite their roots in family history, his fictional counterparts — Mary and also Alistair Heath, an art restorer who spends the latter part of the novel besieged on Malta with British forces — are just a bit too undaunted, or unbroken, by the trauma that the war throws in their path.

Mary goes to work initially at a school, where her first task is to oversee the evacuation of students to the British countryside, and later, after a succession of tragedies, she serves as an ambulance driver, treating casualties of the Blitz. Alistair bears the burden of his combat experience with a wary disassociation, less post-traumatic stress disorder than resigned ennui. “All his senior officers lay rent and scorched,” Cleave tells us, describing the aftermath of one especially brutal battle. “The colonel sat upright at a camp table, bloodless and gray, the line of his mustache expressing indignation, the handset of the field telephone still clasped in his hand.”

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Both appear to shrug off hardship — to face it, yes, but also to know they will get past it, even as the worst is happening. Each is wounded, physically and spiritually, by what he or she has gone through, and yet it is less these wounds, visible or otherwise, than their resilience that resonates.

That, of course, is part of Cleave’s intention; “Everyone Brave is Forgiven” is a narrative of redemption. All the same, it leaves the novel with significant problems because it flattens out the conflicts, rendering them more as device or backdrop than transformative experience.

It’s not that the characters are unaware. Early in the book, thinking of Alistair’s roommate Tom, who is her lover first, Mary considers the circumstances: “Without the war, how would one ever meet an ordinary man like Tom?”

And yet, the thought, with all its social implications, fades beneath a more conventional story, defined by romance and (yes) by pluck. “Soon,” she reflects, “Tom would realize that there was nothing more important than Mary North — that it was only her sorcery causing the planets to stay aligned and preventing the milk from curdling.”

To be fair, Mary hasn’t suffered much at this point, which makes her callowness understandable. War, like any great upheaval, alters us — or it ought to — turning our hearts and psyches unexpectedly. In “Everyone Brave is Forgiven,” however, such a turning never happens, since the characters come to us fully formed.

Mary’s sense of destiny, Tom’s steadiness, Alistair’s diffident gentility — all of these harden, rather than develop, as the novel runs its course. Adversity, for them, is like a suit one puts on, something to wear until it is done. None of the characters here are truly changed, not at the deepest level, which gives the book something of a shopworn quality.

What makes this unfortunate is that Cleave can write. His descriptions of the Blitz and, even more, of Alistair’s shock, his inability to process what he feels and sees, are affecting and sharp. “It happened from time to time,” he observes of the latter, describing the dread that seizes him in moments. “It was just a maddening tic, like getting a popular jingle stuck in one’s head. How one wished that all the gore had never got in there. Still, in this as in all other things, he felt certain he would recover.” It’s the last line that is the problem, for it reveals the novel’s true intentions, which are sentimental at the core.

Author Chris Cleave (Lou Abercrombie)

This is the difficulty with looking back at such a paradigm-shifting event as World War II: 50 million dead, a continent destroyed, and the anxiety of all those years spent in the shadow of devastation, of not knowing what each day might bring. “Everyone Brave is Forgiven” pays lip service to such issues, but it can’t, or doesn’t want to, deal with the complexities; there is no room for them in the story Cleave aspires to tell.

“How hadn’t she noticed this?” Mary wonders in a rare unguarded moment, pondering the stillness of the shattered city. Given what she and Alistair and Tom have been through, we have to wonder: How indeed?

David L. Ulin, a former book editor and book critic for the Los Angeles Times, is the author of “Sidewalking: Coming to Terms with Los Angeles.”

Everyone Brave is Forgiven

By Chris Cleave

Simon & Schuster. 424 pp. $26.99