Catherine, played by Emily Henley, reveals a difficult secret to the two people she trusts most in the world, Claire and Hal (played by Allison Fifield and John Hauser). Learn for yourself during the final weekend of "Proof" at Thunder River Theatre Company. Courtesy photo by Northrup Studios

Editor’s note: This review contains plot details that may be deemed “spoilers”

David Auburn’s Pulitzer Prize-winning play, “Proof”, is a laboratory built to test your interpersonal compass. Thunder River Theater Company’s interpretation, directed by Valley veteran Sue Lavin, is just as honest as it is provocative, stripping bare the human intellect’s ability to create as well as its propensity to destroy.

The play opens on a humble birthday celebration. The birthday girl, Catherine, played by Emily Henley, fends off the predictable concerns of her father Robert, played by Jeff Carlson, over a bottle of cheap champagne on their back porch. Is Cathy making friends? Is she fulfilling her intellectual potential? Cathy’s sole concern, however, centers on the fact that she is now 25 years old. Is she past her prime?

Henley’s strength and clarity, combined with Carlson’s charm and patience, make Catherine and Robert excellent sparring partners. Their fears echo our own, and within minutes the audience feels at home on this dusty back porch somewhere in the South Side of Chicago. Then, in the span of a few lines, everything changes. Catherine’s fear over her own mental well-being thrusts itself into the spotlight, and the audience leans in, intent on discovering her fate.

Despite everything you’ve read, this play is only tangentially about math. At its core, “Proof” is a testament to the tragic cost of genius, and whether or not human relationships have the power to redeem intellectual rot. As Robert exits, we meet Hal, played by John Hauser, and discover that Robert was not an ordinary math professor, but rather a field-altering mathematician with swaths of idolizing students, Hal chief among them.

On the surface, Hal’s interests lie in digesting decades’ worth of Robert’s journals, one by one, combing through them with a careful eye, searching for heretofore undiscovered academic marvels. At the same time, he senses tragedy in Cathy, and attempts to get her out of the house to have the type of fun typical of a 20-something Chicagoan. Cathy, always on guard, doubts his motives, and for good reason. Hal is a thief, and though Cathy calls the police, by the time they arrive she has forgiven him.

The next day, Cathy’s sister Claire, played by Allison Fifield, arrives from New York with her own intentions disguised in coffee, bagels and shampoo recommendations. Claire, like Hal, knows that Cathy is, despite all protestations, not okay, but she has come prepared. Though she stops short of revealing the entirety of her plan, Claire suggests that some time spent outside of Chicago might be good for her sister. Cathy’s response? A definite maybe.

From there, Hal and Claire each attempt to mend Cathy’s broken spirit with offers of housing and of love, only one of which persuades Cathy to open herself up and share the true cause of her despair: her genius. 

The second act winds back the clock four years and gives us a picture of Robert at his mesmerizing, lucid best, before exposing the crippling nature of his insanity, with Carlson’s performance leaving the audience in chills. Meanwhile, in the present, Cathy, Claire and Hal begin to spiral into a cesspool of doubt and toxicity over the true authorship of yet another piece of field-altering mathematical work. As the dust settles, the audience ponders over several crucial questions. 

In the face of a father’s insanity, what does it look like to be a responsible daughter, or a caring sister? Is genius hereditary? What about madness? Can one exist without the other? And, most crucially, what kind of love can best heal a broken mind?

I must admit that after watching just once, I do not have answers to these questions. So, this coming weekend, I will be back in the audience to watch what unfolds on the back porch a second time. I hope, dear reader, that you’ll join me.