"AGNES OF GOD" is a question of faith, an evocative if ineffective mystery set in a nunnery in wintry Quebec. Whispered matins echo in the halls as God's brides wade through the darkness, shutting out the world, when a shriek shatters their silent night.

Minutes later, the sisters find the blood- soaked novice Agnes in her room with a strangled newborn. She has no memory of the birth or even the pregnancy as the mystery begins. The court appoints a forensic psychiatrist to unlock her mind, to solve the crime or find a cure.

Meg Tilly plays Agnes, an ecstatic beauty with a face as pure as a painted madonna's. And Tilly is marvelous in this demanding role, with Jane Fonda, clipped and smart in suede boots and power suits, less effective as analyst to the little nun. Like some working gal's Sigmund Freud, she represents the voice of reason in this medieval setting. Anne Bancroft is her excellent adversary, a mother superior who wants to believe in miracles, to protect Agnes and also this female retreat.

The twilight of an old order and the outsider's effect on an insular society are familiar themes for director Norman Jewison, who explored them far more satisfyingly in last year's "A Soldier's Story," which, like "Agnes," was a play adapted for screen.

John Pielmeier writes the script, with its diluted ending, from his Tony Award-winning play. On screen, his question of faith is reduced to a quibble, with the confrontation between Bancroft, the believer, and Fonda, the fact-finder, well-performed though not profound. The scales are weighted in Fonda's favor. Clearly Agnes is no miracle, but only a mad woman, as Fonda the therapist extracts shocking secrets like a magician pulling flowers from a sleeve.

Cinematographer Sven Nyquist creates a striking setting, influenced by the painter Vermeer. But the rich visuals seem at odds with the spartan content of the screenplay, with skating nuns like penguins on a frozen pond, cows lowing, pigeons flapping, statues weeping, novices in white gowns splayed like crucifixes on the stone cold floor.

We're left with these images when we should be left pondering the cosmos, shortchanged by the saints and the scientists alike, denied our just epiphany.

AGNES OF GOD (PG-13) -- At the Avalon.