If ever a play deserved to be called a "psychological drama," it is "Agnes of God." The tag fits, not only because the plot revolves around the analysis of a young nun by a troubled psychiatrist, but also because playwright John Pielmeier constantly reminds us of the blurred line between sanity and madness.

Agnes is a troubled young novice in a convent run by a kindly Mother Superior. When a newborn is found strangled in a trash can in Agnes' room, she is charged with manslaughter and sent to be evaluated for her fitness to stand trial by a psychiatrist with issues of her own.

The play, presented by Grand Dream Productions, continues through Sunday at the Grand Theater in Elizabeth Borough.

In "Agnes," Pielmeier gives us plenty to think about as he cleverly unveils the skeletons in the closets of all three main characters. The shrink and the older nun clash early and often over Agnes' treatment and that makes for some tense moments deftly driven by Pielmeier's crisp dialogue.

But all too often, those skeletons seem to be conveniently planted by the playwright to support the drama, and his or his character's points of view, while having them grapple with the controversies of sanity, religion, abortion and politics.

For example, is it just coincidence that a doctor and nun who are thrown together by mere fate should both be predisposed by past experience to harbor resentment against the vocation of the other? And how does Agnes end up in a convent instead of going someplace where she could get the psychological help she needs? Pielmeier's explanations are flimsy.

The fledgling Grand Dream Productions once again presents a production that shows maturity beyond its less than one year tenure. Director Laura A. McCarthy runs a tight ship and never lets the action drag. And Ronald J. Gmys' simple set presents a convincing picture of both the psychiatrist's office and rooms in the convent.

Nance Mimless plays the haunted psychiatrist as a dignified woman who can't quite rationalize her biases to herself or her nemesis. Cathy Vonderau gives a bravura performance as the proud and self-assured nun who occasionally gives in to the anger that bubbles underneath.

It is the verbal jousting between these characters that makes "Agnes of God" a riveting drama with actors more than equal to the task.

Stacy Bartlebaugh-Gmys infuses the title character with enough quirky eccentricity to give us a picture of the young nun's severely compromised mental state, but is less successful in capturing Agnes' arrested emotional development in a way that would make the character more sympathetic than annoying.

"Agnes of God" presented by Grand Dream Productions at the Grand Theatre, 207 2nd Ave. in Elizabeth Borough.

Remaining performances are at 8 p.m. tomorrow, Friday and Saturday and 2 p.m. Sunday.

Tickets are $9 and $10. Call 412-384-0504 for reservations.