Scottish filmmaker Bill Forsyth is a maker of miracles, an ingenious alchemist who mixes the extraordinary and the everyday. His films are full of magic made commonplace -- marine biologists who turn into mermaids, mind-altering mists, ice cream mafiosi and people in penguin suits. There's always a mood of the awestruck child, who never stopped believing in the Little People, the Loch Ness monster, the many myths of the British Isles.

The director of "Gregory's Girl," "Comfort and Joy" and "Local Hero" now casts a familiar, though chillier, spell in his first American film, an exquisite adaptation of Marilynne Robinson's novel "Housekeeping." He and Robinson are soulmates -- both artists of longing and landscape, aware of their power to change and shape us.

The glacial mountain lake that is the movie's backdrop becomes not only a metaphor but an inanimate character in this wistful comedy of inconstancy. A railroad bridge crosses the lake, and over that bridge, a vagabond comes home to fictional Fingerbone, Idaho. Christine Lahti, that longtime Hollywood bridesmaid, has this pivotal role of the transient Aunt Sylvie, who has returned to care for her orphan nieces.

Since British Columbia actually stood in for Idaho, Forsyth chose Canadian actresses Sara Walker and Andrea Burchill for the roles of 15-year-old Ruth and her 13-year-old sister Lucille. The girls, whose father deserted them and whose mother drove to her death in Fingerbone Lake, have been raised by a succession of elderly relatives -- "The paperboy was the only one under 60 we'd seen for months," notes Ruth. At first, the girls are delighted with their 35-year-old aunt, a connection with their mother. But soon it seems clear that eccentricity runs in the family. Against the normalcy of the 1950s, the era of covered dishes and a sturdy, stable middle class, the three seem all the odder by contrast.

Sylvie, a gentle, distracted wanderer, is the very symbol of the transience that has shaped their lives. She wanders in the woods and haunts the railway station, shadowed by the girls, who are afraid she too will leave them. Soon the more sensible sister Lucille, embarrassed that her aunt lines her coat with newspapers and naps in the park, wishes Sylvie would hop a caboose. The two girls develop vastly different ways of relating to this bewildering woman -- but both methods spring from a fear of an ever-changing world.

Before they ever came to Fingerbone, their grandfather, a railway man, vanished in the lake in a legendary derailment one moonless night. "The only things they ever found were a suitcase, a seat cushion and a lettuce," says Ruth. The girls skate on their ancestors' graves, practicing figure eights on the frozen lake, which will thaw in spring to flood their house.

Eventually Lucille moves out of the flood-damaged house, which Sylvie has filled with tin cans and newspapers -- her hobo's treasures. Lucille finds comfort in the conventions of Fingerbone, a town where her pioneer grandfather planted the family tree. She moves in with her schoolteacher, and Ruth, awkward, self-absorbed and abandoned again, grows closer to Sylvie. She sees the wisdom of wandering, of outwitting change.

Ruth and her aunt are strange but contented in their ever-more-dilapidated house, but the well-meaning busybodies of Fingerbone decide to take Ruth away for her own good. Convinced that caprice can be controlled with a feather duster, they see madness in this messy, cat-filled house. The futility of housekeeping never occurs to them. And so the oddballs find themselves on trial.

As Sylvie, Lahti beautifully conveys the sense that she's not quite tuned in, wandering in and out like a faraway station on a car radio. Sylvie, a Mad Hatter-esque character, sets the curtains on fire when she lights the candles on Lucille's birthday cake. But she doesn't stop singing as she smacks out the flames.

Lahti's easygoing eloquence and ordinary beauty never overwhelm her young, refreshingly unaffected costars. Walker is especially endearing as the quirky Ruth, who narrates the story. The movie has the feel of a cracked children's story -- as funny as it is full of shadowy, unspoken fears. Robinson, who based "Housekeeping" on her own childhood in the Pacific Northwest, wrote from a lopsided perspective, an oddball angle that Forsyth found suited him just fine. There's a little bit of "Gregory's Girl" in Ruth and a little bit of the gloaming in these Rockies.

Housekeeping, at the Key, is rated PG.