With a pretty solid track record for thoughtful, well-produced theater, local group Kopper Bear Productions returns from yet another short hibernation with a thoroughly enjoyable show. Debuting in New York, David Auburn's family drama "Proof" was a huge success critically, winning a Tony Award, a Pulitzer Prize and quite a bit of attention.

The highly successful drama follows the earthly end of scientific genius as the daughters of a legendary mathematician who has passed away discuss their father's legacy in all of its various forms with each other and one of his former students.

Local theater veteran Paul Troglia plays Robert, the mathematician father who seems to be based somewhat loosely on the legendary John Nash. Robert did amazing work that really advanced the field early on in his life, but the years have taken their toll and his mind seems to be falling apart as he gradually descends into abject mental illness. No longer lucid enough to maintain his duties as a math professor at the University of Chicago, he spends his days filling notebooks with unintelligible nonsense. Troglia brings an inspired sense of personality to the role that reveals precisely the kind of complicated character you would expect out of a math genius.

Some of Troglia's best moments on stage are shared with Kassi Mattera, who plays his daughter Catherine. Unwilling to let her father be placed in professional care, Catherine has looked after him for quite some time. Years of setting aside her personal desires to complete a college education and have her own life have made things difficult for her. Having passed away, he has left her with some rather major decisions on what to do with the rest of her life. Fresh to the professional theatre scene, Kassi Mattera shows a dazzling amount of potential here. Mattera's brief twinges of forced emotion opening night were only tiny imperfections in an otherwise exceptionally enjoyable performance. She has a fascinating stage presence that works well here as she fully becomes the central focus of the plot after intermission.

Brought out by Robert's death, Catherine's sister Claire comes to visit from the East Coast. While Catherine has been looking after her father, Claire has been working a high-paying job in New York to support them. Carrie McGhee is well-cast as the pragmatic, well-grounded sister of the less-centered Catherine. Claire offers to help Catherine move out to New York in a major life decision which Catherine might not have that much control over.

Matthew Huebsch rounds out the cast as Hal, student of the late math genius who visits the house every day to go through Robert's old notebooks seeing if there might be any major breakthroughs there. The character is likeable enough and Huebsch does an excellent job of fleshing him out for the stage, but the character acts largely as a plot device throughout much of the story. The role Hal plays in the plot is really crucial, but he isn't given much substance of his own. Tender moments that arise between him and Catherine seem more like an obligatory romantic afterthought than as the central part of the story that they probably should've been.

It's nice to see a plot focus so closely on the stormy heroic world of influential thinkers. The culture of science gets precious little play in contemporary drama, so it's nice to see it get some stage time, but "Proof" does little to explore it. That is not to say it's entirely divorced from university math culture. Hal mentions a rather misleading bit about older math professors using amphetamines and there's a rather crucial bit in the plot that seems inspired by Andrew Wiles' proof of Fermat's Last Theorem, but for the most part, the plot is really about people.

There really isn't much going on here that couldn't be told in a story about a psychologically troubled genius of ANY kind. It's really too bad that the story of a mathematician couldn't focus a bit more on ... math. As a drama, though, it has its own life beyond the setting. Mattera and Troglia make it breathe wonderfully.

"Proof" runs through Feb. 19 at the Sunset Playhouse in Elm Grove. Tickets are $17 and can be purchased by calling the box office at (262) 782-4430.