A tender and compassionate portrait of a couple whose relationship is ravaged by Alzheimer's disease, "A Song for Martin" is the second film involving the illness in as many weeks. Like "Iris," which is based on John Bayley's account of the decline of his wife, famed author Iris Murdoch, "A Song for Martin" deals with the effect of Alzheimer's on an exceptionally gifted artist and his tirelessly supportive spouse.

Although the films' subject matter and themes are similar, "Martin" takes a more straightforward, uncompromising approach to the disease that makes watching it paradoxically painful and rewarding. Whereas "Iris" tempers Murdoch's descent by repeatedly intercutting flashbacks of the couple in their youth, "Martin" faces the disease and never looks back. Directed by Bille August with unflinching honesty and meticulous attention to character and dramatic structure, this Danish-Swedish co-production is a remarkable achievement.

Following August's relatively unsuccessful forays into large-scale films with international casts ("Smilla's Sense of Snow," "Les Miserables"), "Martin" marks the director's welcome return to intimate dramas. Better suited to working on a smaller canvas, August takes great care to shade every detail of his film, and his efforts pay off beautifully. The film opens at an orchestra rehearsal where acclaimed composer-conductor Martin Fisher (Sven Wollter) catches the eye of violinist Barbara Hartman (Viveka Seldahl). An intense flirtation yields to an affair. Having spent years in loveless marriages, they quickly divorce their respective spouses to marry each other.

Barbara and Martin's first few years together are presented in a passionate and relentlessly upbeat montage. Images of a blissful Moroccan honeymoon are followed by images of the couple composing together, laughing, making love and displaying (for a couple in their late 50s) seemingly inexhaustible reserves of energy.

But their happiness is ephemeral, as Martin begins to show signs of forgetfulness and irritability. Diagnosed with Alzheimer's, he must combat an invisible foe, all the more insidious because Martin is largely oblivious to its symptoms. That the two soul mates should have found each other so late in life renders Martin's illness especially tragic and Barbara's sacrifices all the more wrenching.

Although up to this point Wollter and Seldahl have carried the film equally and effectively, once Martin's decline begins accelerating (which it does a little too quickly, mainly for dramatic purposes), "Martin" becomes Seldahl's film. In a rich and nuanced performance, Seldahl (Wollter's real-life wife) taps into a complex web of rage, frustration, love and loss. As the illness forces Martin to become increasingly passive and withdrawn, Barbara gives up performing to care for him and is determined to fight the disease with her own force of will.

With the slightest of gestures, August says a great deal about the couple's shifting power dynamic: On a second honeymoon to Morocco, Barbara carries the luggage while Martin, dazed, stands nearby. It's a stark contrast to a few years before, when a vigorous and ebullient Martin had carried Barbara across the hotel lobby and into their bridal suite.

As Martin's illness worsens, it appears he won't be able to finish his last great musical work, an opera he had promised to deliver to his manager and promoter (Reine Brynolfsson). In his mind, Martin is still a brilliant composer, but to the rest of the world he has become a shrunken and mentally incompetent old man. As Barbara watches her husband fade, she must decide whether to embrace life again on her own.

Because Alzheimer's is a metaphor for loss in so many ways--the loss of memory, the loss of self-awareness, the loss, for the spouse, of a loved one--"Martin" looks at the composer's life as a sort of unfinished symphony. Within that framework, its dramatic sequences are reminiscent of musical movements that build on one another. From its invitingly upbeat overture to its pathos-filled but ultimately life-affirming finale, "Martin" is a masterfully conducted work.

Unrated. Times guidelines: very graphic and disturbing portrait of Alzheimer's disease.

*

'A Song for Martin'

Sven Wollter...Martin

Viveka Seldahl...Barbara

Reine Brynolfsson...Biederman

Linda Kallgren...Karin

Lisa Werlinder...Elisabeth

Peter Engman...Philip

First Look Pictures presents a Moonlight Filmproduction ApS/Svenska Filmkompaniet production, in association with Film I Vasdt, SVT Drama, TV2 and Helkon Media. Director Bille August. Producers Lars Kolvig, Michael Obel, Bille August. Screenplay by Bille August, based on the novel "Bokem om E" by Ulla Isaksson. Cinematographer Jorgen Persson. Editor Janus Billeskov-Jansen. Music Stefan Nilsson. Costume designer Katarina Kvist. Art director Anna Asp. In Swedish, with English subtitles. Running time: 1 hour, 58 minutes.

Exclusively at Landmark's Westside Pavilion Cinemas through Thursday, 10800 W. Pico Blvd., West L.A., (310) 475-0202.