Fleeting moods: William Eadie as James in the film "Ratcatcher."

Ratcatcher. Written and directed by Lynne Ramsay; in strong Glasgow dialect, with English subtitles; director of photography, Alwin Kuchler; edited by Lucia Zucchetti; music by Rachel Portman; production designer, Jane Morton; produced by Gavin Emerson. Running time: 94 minutes. This film is not rated, shown with a three-minute short, Masayo Nishimura's "Dream," tonight at 9 and Sunday at 3:30 p.m. at the Roy and Niuta Titus Theater, Museum of Modern Art, 11 West 53rd Street, Manhattan, as part of the 29th New Directors/New Films series of the Film Society of Lincoln Center and the department of film of the Museum of Modern Art
WITH: William Eadie (James), Tommy Flanagan (Da), Mandy Matthews (Ma) and Leanne Mullen (Margaret Anne) .

"Ratcatcher," the brilliant directorial debut of Lynne Ramsay, is a gorgeous blend of beauty and squalor, packed with imagery that will play over and over in your head for weeks. It begins with a boy named Ryan spinning while wrapped in his mother's curtains, the cream-colored lace covering his face like a shroud, and the scene shifts from slow motion to real time as his mother angrily pulls him out of the fabric. It's one of the many deft pieces of foreshadowing that Ms. Ramsay allows to seep through the film, the story of 12-year-old James (William Eadie) during a few weeks of his life in the early 1970s.

The movie takes place while a garbage strike in Glasgow leaves the streets lined with festering piles of refuse. "Somebody's chucked out a perfectly good dog," notes a teenage boy as he inspects an animal's carcass while rats of all sizes -- and the filmmaker uses them for several purposes -- dart through the fetid landscape.

James has a knack for trouble. He accidentally drowns a friend -- the boy seen playing in the curtains at the start -- and his pale, inscrutable face has a furrow of guilt etched between the eyes for the rest of the film. His sorrow is sealed when the boy's mother gives James her dead son's shoes. Ms. Ramsay, who also wrote the script, is wholly consumed with filmmaking fever, and her touchstones are evident: "Ratcatcher" could be "The 400 Blows" as directed by Ken Loach. Yet she brings something wholly original to the film. Although "Ratcatcher" flirts with misery, and its palette principally a series of glum earth tones with an occasional vivid splash of color, the immensely talented Ms. Ramsay provides an intimacy that is completely mesmerizing. Rarely has physical wretchedness been rendered with such delicacy.

Her actors have an awe-inspiring openness to the camera that gives the movie a magnetic realism; with the exception of Mr. Eadie, the characters have nothing to hide, and trained actors are seldom so exposed. But it's warped realism because each detail is in place. The treacherous muddy bog of a canal where Ryan drowned, near the squalid housing project in which James lives with his parents and two sisters, keeps drawing him back. Like any other boy, he is fixated on mystery and danger.

The power of "Ratcatcher" comes from its hushed lyricism and Ms. Ramsay's talent for conveying emotional complexity. Despite the setting, it is sweet and soulful, with a confident lightness of touch that allows for pinpoint shifts of mood. Perhaps the reason Ms. Ramsay uses children as her protagonists is for their fleetness of expression; they move from one state to another very quickly. (Their ease brings to mind a line form Yeat's "Sailing to Byzantium": "That is no country for old men").

One of the best scene involves James's relationship with Margaret Anne (Leanne Mullen), the kind of girl who used to be described as easy. It's not what he desires of her, and at one point they play in the tub, scrubbing each other's infected scalps. Afterward, they sit in front of the television set, wrapped in towels while eating sandwiches, like the most innocent married couple in the world. Rachel Portman's score, one of her best, is so spare it's barely there, yet it registers powerfully. (Her works include "The Cider House Rules.") The sound design is specific and minimal, adding to the feeling that the picture is wrapped in a constant dreaminess, like that lace curtain at the beginning. (There are also several other transitions from slow motion to normal speed to deepen that facet.).

"Ratcatcher," which is being shown tonight and Sunday as part of the New Directors/New Films series at the Museum of Modern Art, isn't all nightmare, either. James keeps visiting a new housing development -- a place the family longs for -- and he sits silently, happily, in an empty new tub. As he plays in a vast field behind the uninhabited home, he is seen through a window with bright blue skies and warm yellow grass in a big black frame. The sequence is proof of Ms. Ramsay's bewitching eye and imagination, and "Ratcatcher" is the most lovely debut film in a long time.