There's something definitely alive and trying to crack its way out of the shell of Karen Zacarias's new play, "The Sins of Sor Juana," which is receiving its world premiere at George Mason University's Theater of the First Amendment. The script isn't fully developed, but the thoroughly professional production gives you the clear sense of a talented writer struggling with Big Things.

"Sor Juana" is based on the life of Juana Ines Ramirez de Asbaje, an intellectual child prodigy who lived in 17th-century Mexico and who, at age 12, was invited to join the court of a nobleman. She accepted and spent the next five years reading and writing on humanist and feminist subjects, as well as developing a close friendship with the nobleman's wife. One day she abruptly left to join a convent, where, despite the Catholic Church's efforts to muzzle her, she continued to write. Then one day, also abruptly, she took a blood oath renouncing writing.

Zacarias, a Washington playwright, calls her play "a researched fantasy" about what drove the girl to leave the security of the court and eventually stop doing what she loved most. To wit: Poems that Juana (Maia DeSanti) has published while a nun have landed the convent's don't-rock-the-boat leader, Padre Nunez (Carlos J. Gonzalez), in hot water with the Inquisition.

Flashback to how Juana came to the convent: The viceroy of the court (also played by Gonzalez), not liking the growing friendship between Juana and his wife (Naomi Jacobson), plots to disrupt Juana's forthcoming marriage to another court nobleman. He hires an educated rogue (John Lescault) to seduce her.

As you might guess, the rogue redeems himself by falling in love with Juana, but when she discovers his part in the plot, tragedy ensues and she flees to the convent--where ultimately she renounces writing because the church will let her continue only if she submits her poems for approval.

There's much to-do in "Sor Juana" about individualism vs. conformity and idealism vs. the real world. But Zacarias makes her main point--that those who won't or can't compromise are heroically doomed--a little too easily. Juana is never made to recognize or deal with the destructive selfishness that underlies her belligerent idealism. She vows never to write again because that's better than being censored--not exactly a gut-wrenching decision. But what if continuing to write posed a more morally ambiguous dilemma--one, say, that might force her to question whether her idealism is worth the pain it causes others?

Zacarias's real talent is for intense, one-on-one scenes between people. On a human level, Juana's confrontations with almost every character are absorbing, and director Tom Prewitt rightly lets basic emotional conflicts--vs., say, sentimental ideas--set the momentum and tone of the production.

Jacobson (who doubles superbly as a weaselly nun) animates the viceroy's wife by making her both shrewd and sensitive. Lescault's scoundrel is intelligent without being smug, vulnerable without being soppy. Gonzalez makes for a wonderfully heartless viceroy and an impressively conflicted padre. Jennifer Nelson also gives strong support in two ensemble roles.

The one problem is DeSanti--in a very problematic and difficult role. The young actress has all the adolescent energy of the character and some of her passion for ideas. When Juana is just a kid in way over her head, DeSanti is fine. But as one who has more than just a rote understanding of those ideas, she fails to convince. Then again, I'm not sure a more experienced actress could pull it off.

Anne Gibson's period set and Muriel Stockdale's costumes create a definite feel for a time and place long ago and far away, and Adam Magazine's lighting complements that feeling especially well. Zacarias may not yet be terribly impressive as an ideas dramatist, but she knows how to tap emotional power, one of the indispensable elements of any good drama.

The Sins of Sor Juana, by Karen Zacarias. Directed by Tom Prewitt. Sound design by Mark K. Anduss. With Andrea Maida, John Benoit, Michael Bryant and Angela Lee Pionk. Through Nov. 21 at Theater of the First Amendment, George Mason University. Call 703-218-6500.

CAPTION: In "The Sins of Sor Juana," a young poet (Maia DeSanti) enters a convent after she is seduced by a handsome rogue (John Lescault).

CAPTION: Naomi Jacobson, Andrea Maida and Maia DeSanti in "The Sins of Sor Juana" at George Mason's Theater of the First Amendment.