A lovely intergenerational moment toward the end of Charlie McDowell’s The Summer Book captures the restorative magic of its atmospheric setting on a tiny island in the Gulf of Finland.

Glenn Close, playing a grandmother nearing the end of her life, acknowledges that once-vivid memories are slipping away from her when she can no longer recall the feeling of sleeping in a tent under the stars as a girl. Her 9-year-old granddaughter describes the experience for her, bringing a smile to the old woman’s face: “I remember that … It’s like the whole island shrinks up around you until you and it are like a raft in the sea.”

Adapted by Robert Jones from the novel by Tove Jansson — the beloved Finnish writer and illustrator of the enduringly popular Moomin books and comic strips — McDowell’s screen version remains true to the source material by sharing its attention equally between its characters and the elemental forces surrounding them. You can feel the brisk chill of Baltic Sea waters lapping at the shore; the soft caress of sunshine in a place where it’s always sweater weather; the violence of a storm that whips up without warning.

Evocative sense of place aside, the film is subdued and gentle to a fault. The bare-bones narrative often seems to drift rather than move forward with purpose, occasionally threatening to get carried off by the winds that hammer the island. But on the plus side, the unhurried pacing — call it island time — allows for illuminating attention to detail. The cumulative experience is affecting in its own minor-key way, an appealing throwback to old-fashioned family dramas of a more innocent era.

While the book is fiction, it’s drawn from Jansson’s many summers spent on the rocky, outer-archipelago islet of Klovharu with her niece, in a modest cottage the author built with her brother in 1964. Jansson, whose early life was depicted in the 2020 Finnish biographical drama Tove, spent five months a year for three decades on the island with her life partner, who shot the 8mm home movies seen in an epilogue in that film and on the end credits here.

The deep roots of the writer’s emotional and physical connection to the place provide a foundation for the slender story. Those qualities are fully manifested in Close’s finely etched characterization. The unnamed grandmother is a hardy woman quite content to live with minimal comforts in an unheated, rustic house even as her health declines. She passes on that love of the island — its rocks and mosses and patches of pine forest — to her granddaughter Sophia (bright newcomer Emily Matthews) in intimate exchanges throughout.

The two of them have come to the remote island with Sophia’s taciturn father (Anders Danielsen Lie) in the wake of a staggering loss that is left unspoken for much of the film. But, starting with the desolate look on his face as he picks up a sunhat left behind the previous summer, it becomes clear that the death of his wife has caused him to shut himself off, retreating into his work as an illustrator. Sophia interprets her father’s silence as a lack of love for her since her mother died, and her grandmother intercedes as a mediator only in the most discreet ways.

Despite the decision to adapt the source material in English, the family feels distinctly Nordic. The young girl is petulant and bored at times, playing cards and listening to her grandma’s old-timey records. But Close gives her character a reassuring stillness and a beatific smile, which generally serve as a calming influence on Sophia. Even when she’s hobbling around on the rocks with difficulty, using a gnarled piece of driftwood as a walking stick, the elderly woman’s demeanor remains infectiously pleasant.

Only once does she speak sharply to Sophia’s father, when he bitterly comments on a boatman’s reluctance to come to the house while delivering fireworks for the Midsummer celebration: “The stink of grief keeps him away.” “Or self-pity,” responds his mother.

That feeling seems entirely foreign to her. When Sophia asks, with the bluntness of the young, when her grandmother is going to die, she replies, “Never you mind. Soon.” Her serene acceptance of that inevitability even extends to her kicking off the covers in bed at night and folding her hands across her chest, seemingly more curious than fearful of what the inside of a coffin might feel like.

The grandmother’s creeping infirmity does little to curb her excursions with Sophia. They go by boat to a neighboring island, where newcomers have built a large, modern home that sits intrusively in the otherwise unspoiled landscape. The old woman’s amusing disapproval is barely softened even when the owners turn out to be genuinely friendly.

Another day, they travel to an abandoned lighthouse. Sophia’s prayer for something exciting to happen — “Like a storm. Anything.” — proves fateful. It brings the narrative’s sole sequence of heightened drama, a cathartic shakeup that allows the family to heal.

The one clanging misstep in Jones’ screenplay is to have the father rail at the heavens when he’s caught by the storm in a rowboat: “Is that all you’ve got? Is it?” The moment feels false and overwrought in a movie that otherwise is a model of restraint.

Danielsen Lie (so memorable in The Worst Person in the World) is given such a recessive character to play that even his grief registers as distant. While his display of renewed warmth toward Sophia is a long time coming, if somewhat abrupt, it’s nonetheless poignant. There’s a pleasing cycle-of-life continuum in the way that repaired bond frees the grandmother to let go.

One could quibble that McDowell prepares us for the old woman’s death so assiduously that almost every cutaway in the latter half of the film seems to be setting up her exit. But when the end does come for her, it’s genuinely moving — a peaceful surrender in which her heartbeat gives out as she literally returns to nature. (That can’t be considered a spoiler since there’s no version of this movie in which grandma lives.)

While the time frame is never specified, the production design, costumes and props all suggest the period in which the 1972 novel was written. There’s lots of chunky knitwear, and no cellphones or computers; even the island newcomers’ fancy home could pass for a boxy modernist build from half a century ago.

The set that matters most is the timeless island itself. A rough-hewn rock formation that looks like it was coughed up by a volcano millions of years earlier, it’s surrounded by ice floes that dissolve only for those few precious summer months. While steering clear of postcard territory, DP Sturla Brandth Grovlen captures the painterly late-night sunsets, the pillowy cloud formations, the rippling waters and the tranquil glades — not to mention the breathtaking light — with a beauty that makes you believe in the healing powers of the place.

The environment could hardly be more different from McDowell’s last feature, the claustrophobic hostage thriller Windfall. Nor could the predominantly sedate tone.

Polish pianist Hania Rani’s shimmering score works as a reminder of the melancholy lurking just below the surface of the characters, accompanied by the ever-present sounds of nature: waves, wind, seabirds. In this retelling, The Summer Book is a slim volume, but its unassuming pleasures acquire substance.