A good comedy is a little like madlibs. Knowing what to do with the empty spaces makes all the difference. It’s not just what actors can pull out of a script that makes a comedy funny; often, it’s what a cast can generate on its own—pure creative humor—that makes a play worth seeing.

That is exactly what’s happening at the Loeb Experimental Theatre. George Bernard Shaw’s “You Never Can Tell,” produced by Tatiana K. Wilson ’09 and Geoffrey S. Johnston ’07 and di-rected by Mary E. Birnbaum ’07 is a joyous, breezy production that is more than up to the Irish playwright’s improvisatory wit. It runs through Nov.18.

“You Never Can Tell” is the fourth and final of Shaw’s “Plays Pleasant,” a series of light, satiri-cal comedies that Shaw penned in the early stages of his career. There’s not much of a plot. Instead, a custody battle, a romance, and turn after turn of sparkling conversation float easily along in the play’s seaside setting.

Of course, even the brightest dialogue can sink like rocks without actors who know how to de-liver it. Fortunately, the cast of “You Never Can Tell”—made up almost entirely of freshmen—is very strong. That most of them will be around for the next four years only makes this perform-ance more exciting.

J. Jack Cutmore-Scott ’10, as Valentine, is the show’s playboy centerpiece. As a struggling dentist in the first act, Valentine is uncomfortable and frustrated. Soon enough, he and his landlord, Mr. Crampton (Thomas A. Dichter ’08) are invited to a lunch by the sea with the Clandon fam-ily. It’s the perfect setting for Valentine’s quick wit and crooked smile.

Cutmore-Scott’s performance is unbearably charismatic. Valentine is a bit of a sleaze, but he has the kind of self-deprecating good-heartedness that every final-clubber wishes for.

Cutmore-Scott is an actor who uses each moment so effectively that he occasionally upstages the rest of the cast without a word. As the Clandons and their guests sit down for lunch, Cutmore-Scott begins cleaning his silverware on a napkin. Then, still cleaning, he notices Gloria (Carolyn W. Holding ’10). Then he stops cleaning. Then he realizes that he’s stopped cleaning and starts again, embarrassed. Then he stops again, content to stare. It’s quiet, subtle, and exactly right.

Watching Cutmore-Scott and Holding together, under Birnbaum’s light, able direction, is one of the show’s chief pleasures. Holding—as one of three children who have been taught to intellectualize their feelings away by their philosopher-mother Mrs. Clandon (Ansley D. Rubinstein ’10)—is naive without being oblivious. Whether Holding is angrily lobbing checkers at Dichter’s Mr. Crampton or curling into a heap on the couch, each new gesture is a revelation.

Interactions between the show’s characters bring out both the best and worst facets of individual performances. Alison H. Rich ’09 and Sam D. Stuntz ’10 play Dolly and Phil, siblings who endlessly needle the crotchety, self-pitying, Mr. Crampton. But where the wonderfully aggravating Rich activates Dichter’s angry stuffiness, Stuntz only deadens it.

As Mrs. Clandon’s two younger children, Dolly and Phil represent hyper-education gone wild. Phil, in particular, is a character rich with the kind of verbal weirdness that makes “You Never Can Tell” such an incisive comedy—he insists on calling the dentist Valentine a “gum architect” and frequently references his “knowledge of human nature”—but Stuntz doesn’t quite know what to do with Phil’s quirks.

There are other wrinkles to be ironed out. The furiously paced fourth act is a little histrionic, like farce on a sugar rush, and Friday’s performance was marred by a fairly obvious sound mistake. However, Birnbaum’s touch is so dexterous that small gaffes quickly recede into the background.

The sets, designed by Grace C. Laubacher ’09, are terrific. Her sets suggest just clearly enough what’s actually there—watch how deftly Laubacher indicates a table and canopy—but their strange beauty is what keeps you paying rapt attention. They are surprising, imaginative, and, in one instance that I won’t give completely away, quite touching.

The sets accommodate a cast of characters who find again and again that their intellectual de-fenses have either gone out of date or been knocked down by the business of living. The fresh-ness of perspective engendered by such disorientation is consistently rendered with affectionate grace.

That may be what makes “You Never Can Tell” such a terrific achievement: it does to its audi-ence exactly what it does to its characters. Leaving the Ex on Friday night, I felt a little like Val-ente—disoriented, exhilarated, and happy to have stumbled into something wonderful.

—Reviewer Richard S. Beck can be reached at rbeck@fas.harvard.edu