WILLIAMSTOWN, Mass. — A peculiar purple light native to the Berkshires casts a flattering glow on the valleys of Western Massachusetts. For me, the light of nostalgia also glows there. Decades ago, I was a flunky at the Williamstown Theater Festival, which I recall fondly even though I spent a lot of my time making French toast and getting yelled at.

Flunkies at the festival today — they’re called apprentices — don’t get yelled at much. And their labor now supports a slate of productions whose technical polish and top-drawer casting often approach Broadway levels. Three plays I caught last weekend, here in Williamstown and 40 miles south in Stockbridge, were evidence that the straw-hat days of B-list performers and cardboard flats are long over, and even my memories of dusty classics earnestly revived need revamping.

Still, the work produced in the country these days is not the same as what we usually see in the city: It is often more exploratory and more serendipitous. I doubt, for instance, that S. Epatha Merkerson and Jane Kaczmarek, fine stage actors rarely seen onstage anymore, could commit themselves to several months away from their television careers for a Manhattan run of an oddball two-hander like Jen Silverman’s “The Roommate.” But offer them the chance to do it in a bucolic setting for just a few weeks, and the calculus changes.

As it happens, such chances and changes are the play’s subject. Sharon (Ms. Merkerson) is a sheltered 54-year-old Iowa divorcée without much to do and a large, empty house to do it in. Ms. Kaczmarek plays Robyn, a 56-year-old lesbian grifter and slam poet late of the Bronx. How the two become roommates is unclear, but Ms. Silverman, whose Brontë sisters takeoff, “The Moors,” was recently seen in New York, isn’t interested in the dull details of conventional storytelling. Instead she sets up a kind of chemistry experiment. Can two women of utterly different temperaments and backgrounds help each other? Can they help each other too much?