By DEBORAH YOUNG

A fast-moving, engrossing multiple-character drama that brings the AIDS crisis of the 1980s into laser focus, Andre Techine's "The Witnesses" is propelled forward by a sense of urgency. Despite its grim subject, the powerful storytelling projects the strongly affirmative message that it's a miracle to be alive and bear witness to those who did not survive. This memorable film, one of Techine's best, is in no way limited to gay viewers and should find a footing with general audiences, especially if the overextended ending istrimmed back a bit.

The opening chapter, entitled "Summer of '84, Happy Days," is actually much closer to lively French comedy than drama. Characters are amusingly set up in a lightning-fast opener as effortless as operetta. Novelist and new mother Sarah (Emmanuelle Beart) and her police-inspector husband Mehdi (Sami Bouajila) are going through a crisis because Sarah has no interest in the baby.

Meanwhile, her 50-ish friend Adrien (Michel Blanc), a well-to-do doctor, one night picks up strapping young Manu (Johan Libereau) in a Paris park. He falls head over heels, but doesn't manage to bed the boy.

Slightly off center stage is Manu's sister, Julie (Julie Depardieu), with whom he shares a room in a cheap hotel of ill repute, while she struggles to affirm herself as an opera singer. Their affectionate sibling relationship adds color but little else to the multihued story.

Adrien, Manu, Sarah and Mehdi share a joyful holiday on the French Riviera together, during which Manu almost drowns. His rescue by macho man Mehdi, culminating in mouth-to-mouth respiration, may qualify as the most erotic near-drowning scene on record. In a twist, the two become lovers, and their summer affair flies by in a few natural-looking gay sex scenes that are never voyeuristic.

These happy days end when Manu discovers he has contracted a mysterious new disease.

In the second chapter, which takes place during the winter of 1984-85, the tone shifts to drama. The AIDS epidemic is just surfacing and doctor Adrien throws himself into the war against it with research, conferences and fund-raising. He tenderly nurses the weakening Manu in his home, while Mehdi and Sarah anxiously await the results of their own blood tests.

Pace stays tense until the concluding third chapter, "Summer Returns," aimed at showing that life goes on. In reality, the whole film has a life-affirming message that makes the additional material feel like an unnecessary longueur.

The spirited, richly nuanced screenplay -- co-penned by Techine, Laurent Guyot and Viviane Zingg -- captures the spirit of the '80s as a time of great social freedom, when marriages could be open and sexual choices experimental, fluid and guiltless. Young Libereau embodies this zeitgeist as the carefree, blithe narcissist Manu, whose irrepressible joie de vivre refuses to be tied down by one lover. Characters played by Beart and Depardieu, who unapologetically throw themselves into their work without paying so much as lip service to family life, are something of a shock today.

The biggest stereotype-breaker, however, is Bouajila as the bisexual vice squad cop, refreshingly free of psychological angst about his contradictions. The excellent Blanc makes a warm and reassuring doctor, despite his rather comically frustrated private life.

Julien Hirsch's CinemaScope lensing staves off melancholy by surrounding the multiple characters with bright comedy colors, an impression reinforced by editor Martine Giordano's lively approach to excerpting the key details of a scene like a swiftly thumbed collection of snapshots. Philippe Sarde's unobtrusive score is pregnant with danger and hope.

Camera (color, CinemaScope widescreen), Julien Hirsch; editor, Martine Giordano; music, Philippe Sarde; production designer, Michele Abbe; costume designer, Khadija Zeggai; sound (Dolby Digital/DTS), Jean-Paul Mugel. Reviewed at Berlin Film Festival (competing), Feb. 12, 2007. Running time: 114 MIN.

With: Constance Dolle, Alain Cauchi, Lorenzo Balducci, Raphaeline Goupilleau, Michele Moretti, Bertrand Soulier, Jacques Nolot, Xavier Beauvois.