It's a neat piece of stage -- or screen -- business, and it tells you everything you need to know about the central characters in "Doubt."

The year is 1964 and Father Flynn (Philip Seymour Hoffman) has been invited to the office of Sister Aloysius (Meryl Streep), principal of St. Nicholas School in the Bronx, ostensibly to talk about a Christmas pageant.

She ushers the priest into her office and he takes her chair -- the one behind her desk, the seat of prominence and power in the room. Sister Aloysius is flummoxed and peeved but she sits while a younger nun, Sister James (Amy Adams), nervously serves tea.

The topic of secular songs quickly gives way to the role of the church in the community, intolerance and then the real matter at hand: Whether the priest acted inappropriately with a 12-year-old altar boy.

"I object to your tone," Father Flynn says. "It's about arriving at the truth," the older nun counters, and the battle lines are drawn and the combatants dug in.

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'Doubt'

3 1/2 stars = Very good
Ratings explained

• Starring: Meryl Streep, Philip Seymour Hoffman, Amy Adams, Viola Davis
• Rating: PG-13 for thematic material
• Web site: doubt-themovie.com

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Change electrifies the air, thanks to the Second Vatican Council, the year-old assassination of President Kennedy and the symbolic acceptance of the school's first black student, who also happens to be at the center of the tug of war between priest and principal.

"Doubt" is based on the John Patrick Shanley play that swept the 2005 awards season, picking up every major honor, including the Pulitzer Prize and Tony Award for best play. Shanley, an Oscar-winning writer for "Moonstruck," adapted his play for the screen and directs it.

It's a joy to behold Streep and Hoffman circling each other like boxers in the ring. They might as well be Ali-Frazier as she jabs with suspicions that harden into certainty and he punches back with incredulousness and umbrage.

Innocence is in the eye of the beholder, and maybe the boy's beleaguered mother (Viola Davis) has other considerations as she reveals the tensions roiling her family. She doesn't have much screen time but, like any great actress, doesn't need it to make her character come alive.

Sister James, meanwhile, struck the match to the tinder but is conflicted as a new teacher, a resident of the convent where she sees another side of Sister Aloysius, and a Catholic who comes down on the side of modernity and has some accusations of her own.

Shanley has opened up his play to flesh out the classrooms, church pews, Sisters of Charity convent and, briefly, neighborhood of his creation. Anyone who attended Catholic grade school in the 1960s will recognize the girls' white chapel veils bobby-pinned to their hair, the no-nonsense discipline, the special status of altar boys and the deferential treatment of priests.

The writer-director tilts his camera at key moments, as if intentionally throwing us off balance. Shanley manages to take amorphous concepts -- doubt, truth, certainty, guilt -- and their consequences and explore them in dynamic fashion.