If your first instinct upon seeing the title “The Guernsey Literary and Potato Peel Pie Society” is to say, “Well, that’s a mouthful,” rest assured that Mike Newell’s film has you covered, for a secondary character does the very same. Indeed, pretty much everyone in this crumbly oatmeal biscuit of a movie does and says exactly what you’d expect of them: based not on the logic of real life, of course, but the cozy conventions of umpteen twee heritage Britpics before it. For Sunday-afternoon comfort-viewing purposes, it’s no problem that “Guernsey” — which follows the post-WWII escapades of a winsome London writer (Lily James) on the eponymous isle — doesn’t stray from its inevitable course as a town-versus-country love triangle. That it offers no surprises as a nominal wartime mystery, however, is rather more bothersome, particularly as what should be a perky trifle trudges past the two-hour mark.
“You already know what books can do,” the heroine is advised in “The Guernsey Literary and Potato Peel Pie Society,” which itself arrives on screen with some assurance on that front. Based on a posthumously published 2008 bestseller by U.S. author Mary Ann Shaffer and co-writer Annie Barrows, it’s one of those films rather perversely dedicated to celebrating the power of the written word, even as it jettisons reams of its source material in the name of cinematic simplicity. (Perhaps not even cinematic: “Guernsey” plays in many respects like a scaled-down miniseries, standing it in good stead for its planned Netflix release in the U.S. and other territories.) Shaffer and Barrows’ short, breezy novel wasn’t aiming for Brontë to begin with, but it’s received soapier treatment still in the slick hands of co-writers Don Roos (some way from “The Opposite of Sex”), Thomas Bezucha (“The Family Stone”) and Kevin Hood (“Becoming Jane”).
Between them, they’ve disentangled the novel’s dramatic and romantic complications to a fault; if it’s possible to merely amble in place, that’s what the storytelling in “Guernsey” does for protracted stretches of screen time. At least that über-quirky title is explained upfront: The society in question is named as an imagined alibi by the eldest and drunkest (Tom Courtenay) of several merry revelers out past curfew on the Nazi-occupied island. After the fact, it becomes a makeshift book club and an outlet for revolutionary spirit among friends, led by defiant firebrand Elizabeth (Jessica Brown Findlay).
Several years and some key traumas later, sturdy-hearted farmer Dawsey Adams (Michiel Huisman) writes about the Society to successful London journalist and author Juliet Ashton (James), having found her name inscribed in one of their moldering second-hand volumes. To the consternation of her editor Sidney (Matthew Goode) and American military boyfriend Mark (Glen Powell), she’s compelled to visit Guernsey for herself, though not before accepting the latter’s marriage proposal; one look at Huisman’s pained puppy-dog eyes, however, should be enough to tell any sentient viewer that this engagement isn’t likely to prove binding.
Hiding her whopper of a rock and cheerfully taking to the country air, Juliet gradually ingratiates herself with Dawsey and the Society’s other members, including lonely ginmaker Isola (a fine Katherine Parkinson, deepening and dignifying a slender sad-sack part) and fretful, clammed-up mother bear Amelia (Penelope Wilton). The more embedded she gets, the more the nervously unexplained absence of Elizabeth gnaws at her: Let the amateur detective work begin. The problem, however, is that the circumstances of Elizabeth’s disappearance are neither particularly intriguing nor, as the rather straightforward investigation unfolds, terribly surprising: Juliet’s sleuthing strategy consists mostly of asking the same questions of the same people until they get honestly answered, while nittier-grittier details are thanklessly delegated to Mark, mostly offscreen, in London. Miss Marple would have this licked in a morning, with time left over for tea and crumpets.
“It’s so compelling!” Juliet exclaims as yet another pointlessly buried secret comes shruggingly to light — the script, by this point, actively straining to convince audiences to agree with her. Happily, the relatively untaxing nature of her snooping affords Juliet plenty of time to devote to the equally urgent matter of chastely bonding with Dawsey in his fields, glazed in buttery, improbable perma-sunlight by cinematographer Zac Nicholson. Less happily, James and Huisman — both appealing, personable performers in their own right — never quite spark as a pairing, their supposed soul connection playing largely as polite rapport. If James carries proceedings with amiable pluck, “Game of Thrones” star Huisman (his accent ebbing and flowing with the Guernsey tides) is less comfortably cast in these twinkly surrounds. Their chemistry deficit makes ensemble MVP Powell, cannily mixing American-abroad glibness with harder flashes of feeling, seem doubly hard done by.
At least everyone looks splendid in costume designer Charlotte Walter’s perfectly cinched 1940s fashions, which give a rakish movie-star hang even to a Guernsey farmer’s baggy sackcloth trousers. That her ace duds here recall her lovely work on last year’s “Their Finest,” however, rather underlines how little else in Newell’s film matches the bittersweet blitheness of that similarly pitched wartime jaunt. Undemanding yet never quite effortless, agreeable yet never quite engrossing, “The Guernsey Literary and Potato Peel Pie Society” has fewer stumbling points than its loopy title, but that title sticks for longer than the rest of it.