"Emilie: La Marquise Du Châtelet Defends Her Life Tonight" begins in the mysterious afterlife of the title character. The 18th-century noblewoman was a renowned physicist, whose theories refuted Isaac Newton, then the bedrock of contemporary physics, and were precursors to Einstein.

She was also Voltaire's lover, which gives the play a real spark.

In a clever conceit, Theatre Pro Rata stages this brilliant play in a chemistry lecture hall at St. Catherine University. Under the thoughtful and continually inventive direction of artistic director Carin Bratlie, this is high-minded, crackling entertainment.

Lauren Gunderson's script captures the thrill of scientific inquiry, and that's infectious. More important, she balances scientific discourse with the heightened language of a comedy of manners.

The risqué dialogue between Emilie and Voltaire sizzles with stylish repartee, as the play comes to have much to say about gender politics.

Shanan Custer is primarily known as a comic actress, and her Emilie is a woman of droll wit, with the exuberant spirit of a maverick.

But she is equally successful in the dramatic heavy lifting of the character's struggle to make sense of her life, to understand the nature of love and of knowledge. She is especially strong in the tragedy.

The final moments become overly abstract and metaphysical, but Custer carries them off, imbuing the ideas with a deep emotional sense.

As Voltaire, Matt Sciple provides a smart foil, dashing as the great celebrity, capturing the intellect and the passion of that great mind and ego.

Amy Bouthilette, Daniel Joeck and Delta Rae Giordano each play several characters, nicely focusing the attention on the central relationship.

Set designer Julia Carlis makes ingenious use of the space, with the large lab table at the center and a backdrop of blackboards. Even under the classroom fluorescent lights, she creates a sense of period, ably assisted by Mandi Johnson's costumes.

Audiences are encouraged to leave a little extra time to find their way around the St. Cate's campus. But it's well worth the effort. This is one of the most original and engaging shows of the year.

William Randall beard writes about theater.