Few novelists have remained at the top of their form as long as P. D. James has. Though her new Adam Dalgliesh mystery isn’t among the 88-year-old writer’s best (as The Lighthouse, published when she was a mere 85, certainly is), the book is strong in ways that have always made James worth reading: it has complex, convincing characters and seriously engages with spiritual and moral issues. And James seldom slights well-plotted suspense—that essential ingredient of a good mystery.

In lesser mysteries, we know only enough about the murder victims to give suspects a plausible motive for the crime. But Rhoda Gradwyn, who is murdered some 80 pages into this novel just as she prepares to begin a new life, is one of James’s most fascinating characters. A renowned investigative journalist who bears the physical and emotional scars of an abusive childhood, Gradwyn has given many people reason to dislike her. The secrets she was forced to keep as a child have led to a lifelong obsession with other people’s secrets. She has become “a stalker of minds.”

Yet as they investigate Gradwyn’s murder, Adam Dal gliesh and Kate Miskin, James’s fair-minded detectives, find her strangely sympathetic. Dalgliesh feels comfortable in her house—a house that strongly reflects Gradwyn’s traits. Both find her writing intelligent and fair. Though, like many people who have never been loved, she is cold and overly reserved, it’s hard for the investigators not to be won over by her imaginative identification with London and the city’s rich history. And the reader knows something that the novel’s other characters can only begin to guess: Gradwyn was on a road to redemption.

The story is set in a posh private clinic, a historic manor house where a talented plastic surgeon operates on rich patients. Here Gradwyn has come to remove a deep scar from a wound inflicted by her father some 35 years earlier. As she tells the surgeon, she “no longer has need of it.” The novel’s first part reveals to readers what remains a mystery to the rest of the characters—the process by which Gradwyn forgives her father, relinquishes her fascination with revealing other people’s secrets, and prepares to begin the new life that the scar’s removal signifies. By the time she is smothered in her bed during the night after her successful operation, presumably by someone closely associated with the manor, her life has reached a kind of psychological and spiritual completion.

Forgiveness is one of the themes of this novel, in which James attempts to sum up some of the insights she has garnered during a long lifetime. It dominates the novel’s distracting subplot, which has to do with the rape and assault of Clara, a friend of Dalgliesh’s fiancée, Emma Lavenham. The novel ends with Clara’s musings about her attacker: “It wasn’t possible to understand him or to forgive . . . but . . . it was possible not to cherish unforgiveness, or find vengeful consolation in the contemplation of his imprisonment. It was for her, not him, to decide how much she had been harmed by him.” And it’s fitting for James, a lifelong Anglican, to conclude these musings with a quote from scripture: “Whatsoever thing from without entereth into the man, it cannot defile him; Because it entereth not into his heart.” The murderer, revealed perhaps too early in the novel (uncharacteristically for James), refuses to undertake or is incapable of pursuing the kind of honest self-examination necessary for such clear-sightedness and, thus, for redemption.

James has said that the motive for murder that interests her most arises from disordered love—from the misguided attempt to protect or avenge someone one loves. She finds this motive particularly rich because it arises from something that is in itself good, as she told me during an interview some years ago. She is fascinated by the complex puzzle of why people who are educated and law-abiding, who should be able to understand their motives and have more insight into themselves and others than many people do, would commit murder.

In this book, as in The Lighthouse, James focuses on disordered or abusive relationships between parents and children, where the absence of love can have consequences as deadly as does the excessive desire to avenge or protect. James is anything but an environmental determinist; no one in this novel has had an easy childhood. But most people sooner or later make peace with their past, as Gradwyn does, and lead good and productive lives. Only a few commit the worst of all crimes. What makes the difference? James believes in original sin. She believes that everyone is capable of great evil. But she also believes in the grace that allows people to see clearly and to choose the good.

It’s probably James’s belief in original sin that makes her novels seem overly dark to some—even, as one friend said, rather nasty. She doesn’t shy away from showing the physical horror of murder or the dark disorder of a murderer’s mind. Few of her characters radiate cheerfulness, and her British humor may be lost on most American readers. But many admirable people populate her books. Some of this novel’s minor characters are not only the most likable, but the most memorable: an inner-city priest with a brood of young children; the principle of a progressive inner-city secondary school; and Lettie Frensham, a 60-year-old woman who must decide what to do with her remaining years. Warmer or less devious than many of the book’s major characters, they are its moral compass. And though Dalgliesh and Miskin are their usual reserved, emotionally contained selves, some overt acts of caring friendship—rare in the series until now—pass between them.

What keeps this book from being one of James’s best is that she seems to have lost some of her interest in plotting. Such mystery staples as the scenes where suspects are gathered together in the library or individually questioned become a bit tedious, and it’s too easy to guess the identity of the murderer. James seems far more interested in motive than in the mechanics of the plot.

She has written each of her latest books with the awareness that it could be her last. This novel has an especially elegiac tone, evident especially in Dal gliesh’s musings on his long career and his conclusion that he may have had enough of murder. The sense of an ending drawing near may also account for the care with which James wraps up the characters’ lives—reuniting lovers, sending some people off to do good in foreign lands and settling others into appropriate marriages.

Dalgliesh and Emma will be happy, we’re assured, and the novel ends with a kind of summation of life’s meaning, in Clara’s words: “The world is a beautiful and terrible place. Deeds of horror are committed every minute and in the end those we love die. If the screams of all earth’s living creatures were one scream of pain, surely it would shake the stars. But we have love. It may seem a frail defence against the horrors of the world, but we must hold fast and believe in it, for it is all that we have.”