Grade: C+

In an author’s note placed at the front of “Bridehead Revisited” to stave off questions about how autobiographical the 1945 novel was, Evelyn Waugh wrote, “I am not I; thou art not he or she; they are not they.” In light of Julian Jarrold’s film, one might be tempted to add “and it is not it.” This is a very handsome period picture, with gorgeous settings, great attention to detail, lovely widescreen cinematography and a stellar British cast. But it’s an almost perversely wrongheaded adaptation of the book.

It must be said that “Brideshead” is a tough nut to crack. Waugh said that its theme was the operation of divine grace in human life, and religion and theology—specifically, the Roman Catholicism to which the author had converted—are central to it. Waugh might in later years have expressed dissatisfaction with the novel, but it remains what it is, and it’s extremely difficult to translate to the screen what he attempted in it—to show how God’s mercy intervenes in human affairs in unexpected ways through the remembered relationships that the cynical Charles Ryder has over the years with members of an aristocratic Roman Catholic family. An upper-middle-class fellow with artistic ambitions, he meets the younger son, the childlike aesthete Lord Sebastian Flyte, at university, and they become fast friends. Their closeness brings Ryder into contact with the members of Sebastian’s family, whose ancestral home is the magnificent Brideshead estate. There’s Sebastian’s smoothly imperious, religiously dogmatic mother Lady Marchmain; his stiffly, almost comically, proper older brother, Lord Brideshead; and his two sisters, the beautiful Lady Julia and young, cocky Lady Cordelia. On a trip to Venice Charles also meets Sebastian’s father, Lord Marchmain, who left Brideshead (and his wife) long ago and is living “in sin” there with his mistress Cara.

In the book, Ryder observes several members of the Brideshead clan “pulled back” to the faith they’ve rejected in various ways, even as he looks upon that faith with an agnostic’s jaded eye: Sebastian, after descending into alcoholism, is drawn toward monasticism, and Lord Marchmain, brought home terminally ill, makes an unexpected choice when faced with the prospect of dying without absolution. Julia—with whom Charles entered into a romantic relationship after both had decided to seek divorces following unhappy marriages—is faced with a decision whether to wed him despite Catholic dictates to the contrary. Even Ryder, returning to Brideshead years later as part of a military billeting during World War II, signals that’s he’s converted, too.

The screenplay by Jeremy Black and Andrew Davies doesn’t ignore any of these episodes, but its heart doesn’t seem to be in them. Indeed, the writing seems far more comfortable with the dismissive treatment of Catholic belief and ritual that arises from Ryder’s jaundiced perspective. And in any event it throws the religious moments into the shadows by recasting Waugh’s narrative into something much more conventional. In the process it coarsens virtually every important aspect of the original while maintaining an almost preternatural surface gentility.

Take the first act. The book is subtle in its treatment of the relationship between Sebastian and Charles. Here it’s turned into an overtly homosexual, or at least homoerotic, affair. And not just that. Though in the novel the intimacy between Charles and Julia doesn’t start until many years later, the movie posits that it begins early on, and that the discovery of it is the catalyst that sends the jealous Sebastian into his downward alcoholic spiral. Moreover, a thread is added to the mix that turns Ruder into something like a social climber whose mercenary tendencies are revealed in an economic arrangement he makes with Rex Mottram, Julia’s husband (a character made into a caricature here), to secure her divorce—an act completely absent from the book, and which (rather than her religious doubts) is then posited as the reason behind her change of heart regarding remarriage. Even the characterization of Ryder’s father—here made into more of an emotionless monster than a charming eccentric—is a major change.

Taken individually, these alterations are regrettable; taken together, they constitute a pattern that really betrays Waugh’s intent. To be sure, by transforming the story into something contemporary viewers will find more psychologically credible and “human,” they may make the film more accessible to audiences looking for highbrow but ultimately undemanding British period drama of the Merchant-Ivory school, but they don’t accurately reflect the deeper concerns of the original. This isn’t even a Cliff’s Notes treatment—it’s not so much “Brideshead Revisited” as “Brideshead Rewritten.”

Within the limitations of its approach, it must be said, the film has its virtues. It’s beautifully shot by Jess Hall on magnificent locations (including Castle Howard in North Yorkshire, which once again stands in for Brideshead, as it did in the 11-hour 1982 mini-series shown in this country on PBS). It’s directed with style, if not much energy, by Jarrold (whose “Becoming Jane” also took liberties). And it boasts a solid cast, led by Emma Thompson and Michael Gambon, who bring understated elegance to Lady and Lord Marchmain. Matthew Goode makes a handsome but rather stilted Ryder; he often seems to be channeling Jeremy Irons, who starred in the mini-series. Ben Whislaw (of Tom Tykwer’s “Perfume”) overplays Sebastian somewhat, dandifying him a bit much, but his extravagance is certainly eye-catching, and Hayley Atwell makes Julia seductive and (in the last reels) passionate.

If you don’t know “Brideshead Revisited,” you may find this radical transformation of it into a more much conventional period romance reasonably enjoyable, in a “Masterpiece Theatre” sort of way. If you do, you’ll probably be appalled by what’s been done to it. Thankfully there’s always the mini-series to go back to; it’s far more faithful in every sense of the word.