Frozen, the Tony Award-winning play now being presented by the Warehouse Performing Arts Center in Cornelius, is an experience to “shake the soul and let the glory out.”

Midway through the second act, I began to weep profusely. But they were the kind of tears that fall from heaven. For I suddenly knew – call it an epiphany, if you will – that it was time for me to forgive my sister.

We don’t often get to experience theater that literally changes our lives. Even if others are not moved to such profound insights as I was, this play about forgiveness is sure to leave a mark on anyone who sees it.

The 1998 play by Bryony Lavery is well-written, and the direction by Divina Cook is strong. And the closeness of the 50-seat Warehouse PAC creates an intimacy between actors and audience that is riveting and intense. At intermission, my companion said to me, “How can we possibly talk about anything after that?”

But it is the performance of Anne Lambert that makes the play so emotionally compelling. She plays Nancy, whose 10-year-old daughter has been murdered by a serial killer.  She begins as a grief-stricken, angry woman whose despair is so deep you cannot imagine she will ever be able to pull herself out. Yet that is just what she does as she journeys through the bleakest parts of her psyche – and emerges from the soul-cleansing a new woman. It is a testament to the resiliency of the human spirit and is never maudlin or overly sentimental.

Lambert’s performance is mostly a series of quiet monologues.  What makes the character so believable is that the actress physically changes before our eyes – not just the expressions on her face, but the way she holds herself and moves.  When she forgives the murderer, she is liberated, not jus in heart, but in body.

John Cunningham as Ralph, the demented killer, is creepy and tormented, yet is always able to elicit our compassion and pity.  He, too, experiences a catharsis, that while sadder than Nancy’s, leaves the audience with a soothing sense of closure.

I must admit I found the third character, Agnetha (played by Annette Saunders), an irritant. She is a scientist who studies the brains of serial killers and whose work explores the nature of heinous acts. It is her scientific explanation that lays the groundwork for our compassion for Ralph and provokes uncomfortable questions about the nature of evil.

She is dealing with her own demons, and her introductory scene of grief is heartbreaking.  But after that, I found her too cold, too rational and too emotionally distant.  While Nancy and Ralph undergo emotionally moving and fascinating transformations, her character remains stagnant and flat. Her soul-searching is perfunctory at best.

I suspect many of you who have read this far are wondering what I said to my sister after my epiphany.  She died a year ago, so I can no longer tell her directly. Yet I like to think her spirit knows and that my forgiveness has given her some kind of peace – just as it has me.

As the Bard wrote in The Merchant of Venice, “the quality of mercy … is twice blessed. It blesseth him that gives and him that takes.”

‘Frozen by Bryony Lavery Through Feb. 13: Thursdays – Saturdays, 8 p.m.; Sundays (Feb. 6 and 13) 2 p.m.  General Admission: $20 The Warehouse Performing Arts Center 9216-A Westmoreland Rd., Cornelius; 704.619.0429 www.warehousepac.com