ALTHOUGH THE state of doubt is often eschewed as destabilizing and undesirable, playwright John Patrick Shanley laments that "there is no room or value placed on doubt, which is one of the hallmarks of the wise man." His play Doubt: A Parable, a taut, challenging TheatreWorks production, provides plenty of room for doubt.

When school principal Sister Aloysius (Kimberly King) suspects the parish priest of "interfering with" young Donald (the only black student in this 1964 Catholic school), she's determined to uncover the truth. The play has touched down amid Vatican II's modernization, and while Father Flynn (Cassidy Brown) encourages updating the curriculum—singing "Frosty the Snowman" in the Christmas pageant—Sister Aloysius is a force for the past: "'Frosty the Snowman' espouses pagan belief in magic," she curtly tells Sister James (Kristin Stokes).

As someone who has always lived by the heart, Sister James is caught between superiors, the man whose work she admires and the woman who seems to be right. She only knows that following Sister Aloysius' advice diminishes her joy of teaching. In this parable, Sister James represents anyone who has tried to balance justice and compassion.

In the inevitable confrontation between these two forces, Father Flynn asks Sister Aloysius, "Where is your compassion?" and she replies, "Nowhere you can get at it." This tradeoff, compassion for righteous certainty, is at the heart of the play's questions, which are foregrounded with thoughtful detail by directors Vickie Rozell and Robert Kelley.

Father Flynn's sermons, sent out to the audience from the apron, signal that the audience is meant to weigh in as part of the process. Early on, we indulge Sister Aloysius, meeting her extreme rigidity with laughter. But as her trap closes on Father Flynn and repercussions billow outward to touch the innocent, tension replaces humor. The directors excite this one-act cyclone of a play with precision pacing. Exchanges in which the cock-sure Aloysius debates morality with Sister James or Father Flynn quicken in pace like a fevered bidding war for a corner on truth.

In spite of the title, the story provides a hard look at certitude, its power and its costs. Even the audience must examine how little proof it takes to begin to doubt the affable Father Flynn. Strong acting sets the audience up. King makes Aloysius relentlessly self-assured, embodying the Sister's cold cynicism without being shrill or peckish. And Brown, somewhat buoyant, somewhat irreverent, gives us a Flynn who is both admirable and impeachable.

Into this clerical struggle comes Mrs. Muller (Tamiyka White), mother of the boy in question. Costume designer Jill Bowers has put her in a passion-red skirt suit, which contrasts with both the obscuring clerical robes and the browns and blacks of Tom Langguth's set. From the principal's office to the stone courtyard with winter-bare trees, the world is colorless and hibernating before Mrs. Muller arrives—with one exception: the colorful stained-glass windows of the church where Flynn gives his sermons.

Through those windows lives a complex world of color, Mrs. Muller's world. Mrs. Muller embraces doubt as solace in a world stacked so that black or white, you lose, and at this performance, her short but beautifully acted scene garnered an outburst of applause. White presents Muller's forthcoming, controversial dialogue gazing down, halting, hands folded in her lap. While ever respectful, Muller's line of reasoning is simply outside Sister Aloysius' box.

And the audience cheers seem to indicate some relief in recognizing that Sister Aloysius' airtight worldview has a crack in it. But this has to make us wonder why we, like Sister James, are so easily intimidated by morality crusades or black-and-white thinking. Shanley doesn't claim that compassion must be at odds with righteousness; he only asks what happens when it is. And his doubt-ridden ending leaves the audience to judge and reflect on the dilemma.

DOUBT: A PARABLE plays Tuesday–Wednesday at 7:30pm, Thursday–Friday at 8pm, Saturday at 2 and 8pm and Sunday at 2 and 7pm through Aug. 10 at the Lucie Stern Theatre, 1305 Middlefield Road, Palo Alto. Tickets are $24–$64. (650.903.6000)

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