Tom Stoppard's masterful play, set on an English estate, deals with a brilliant teenager, Thomasina Coverly, who in 1812 jots down a series of equations that anticipate chaos theory. Her tutor is a friend of Lord Byron. More than 180 years later, a handful of young scholars find not just Thomasina's notebook, but also murky suggestions that Lord Byron killed a minor poet in a duel on the estate grounds. They chase down these mysteries with different degrees of cleverness and professional self-interest -- one pompous scholar named Bernard Nightingale thinks he can make a career out of his theory of Byron's duel -- while we watch the real story unfold in scenes that alternate between centuries but never leave the same antique drawing room. Stoppard's likable characters talk about the Enlightenment, Romantic poetry, English gardening, and chaos theory; you sense the ambitious playwright working to reconcile the old Romantic war with reason using late-20th-century physics. None of this erudition gets in the way of the story, though, as it does in other Stoppard plays, and Arcadia is as sturdy and delicately balanced (and dispassionate) as a Bach cantata. The young Alison Walla plays a tart Thomasina; Christopher Kelly has authority and charm as her tutor, Septimus Hodge; and Jennifer Erin Roberts plays a skeptical, stable writer named Hannah Jarvis to counterbalance J. Paul Boehmer's gasbag Nightingale. Not all of the acting is perfect -- Amanda Moody's performance as Thomasina's mother, Lady Croom, goes way over the top -- but director Robert Kelley manages to steer the show with an invisible, light-handed grace.