A trenchant new comedy by Bryna Turner features Mary Wiseman in a comic tour-de-force as the guest most likely to make a scene.“I’m starting to think this wedding needs a villain,” says Carlo, as if the one she has semi-crashed were a murder mystery.Certainly there are plenty of suspects behaving badly, chief among them Carlo herself, a freelance snark machine with a hole in her heart and an alcohol-fueled taste for the piercing aperçu. She terrifies the children’s table with a hellish lesson about the fate of romance: “the worst pain you’ll feel in your life.” She’s also, uh-oh, the bride’s former lover — you know, the one who neglected to R.S.V.P.Though it’s not by a long shot the first time a comedy has mined the nuptials-with-an-ex-to-grind setup, Bryna Turner’s “At the Wedding,” which opened on Monday at the Claire Tow Theater, offers a fresh and trenchant take on the genre. And in Carlo, the bruised heart of the story, it offers the actor Mary Wiseman, with her curly red mop piled high like a lesbian Lucy, a brilliant showcase for her split-level comic genius.I say split-level because, with Wiseman, there’s always one thing going on verbally upstairs and another going on emotionally in the basement. Sipping from an endless succession of wedding libations at some kind of barn in Northern California, her Carlo makes like a porcupine, shooting quills in the form of quips. Was not the ceremony, she gaily asks another guest, “aggressively heterosexual”? (Her ex, Eva, has married a man.) “I almost thought they were going to start checking for her hymen right there in front of us.”The lines are funny; Turner has a boxer’s sense of the two-punch rhythm of jokes. But it’s Wiseman, who first stole the spotlight as a brilliantly dim belle in Branden Jacobs-Jenkins’s “An Octoroon,” who makes them hilarious by making them sad at the same time. Though focusing her ire on the wedding as a false celebration — “I’ve seen more convincing fire drills,” she says — Carlo is really gnawing at the scar of attachment itself. For those who are no good at staying in love, gift-grabs like this are worse than embarrassments; they’re torture.The sprightly, 70-minute LCT3 production, directed with wit by Jenna Worsham, gives us both of those elements right away. A gigantic, labial paper-flower chandelier hangs from the ceiling of the set, by Maruti Evans; a jaunty but ominous “Til Death” sign radiates its neon message amid Oona Curley’s string lights and lanterns. But neither the play nor the design completely endorses Carlo’s one-sided view. The eclectic playlist (sound by Fan Zhang) is exactly the kind you’d want to dance to, and the flattering costumes (by Oana Botez) are the kind you want people to dance in.It’s especially smart that Eva (Rebecca S’manga Frank) is allowed to look glorious in a truly elegant gown; she’s no comic-book bridezilla, and though we never learn exactly what happened in her relationship with Carlo, it’s evident she had good reason to end it. And if Carlo, in grief, has become an admonitory fury — Turner explicitly compares her to the Ancient Mariner in Coleridge’s poem, accosting wedding guests with her ghastly story — her legitimate beefs never completely obscure our view of the other partygoers as jumbles of kindness and monstrousness.The play is structured to reveal that contradiction in a series of well-acted, one-on-one encounters with Carlo. An undermine-y bridesmaid named Carly (Keren Lugo) tells her that “it wouldn’t be any failure if you decided to leave,” but later returns to comfort her. Eva’s sloshed mother, Maria (Carolyn McCormick), dismisses the R.S.V.P. gaffe but then dismisses Carlo herself. A guest named Eli (Will Rogers) confides that he intends to propose to his partner at the party, thus (as Carlo warns him) “emotionally hijacking” the festivities — which is apparently her job, not his. Yet he is far more complex than he at first seems.Rebecca S’manga Frank, left, plays Wiseman’s ex, but she is no comic-book bridezilla.Sara Krulwich/The New York TimesSo is Leigh (Han Van Sciver), an androgynous Lothario who uses they/them pronouns. Leigh’s flirtation with Carlo — suggesting they ditch the party for a romp somewhere else — at first seems innocent enough, even though Leigh’s brother is the groom. When that innocence is later brought into question, and the selfish side of sexual freedom surfaces, the play still refuses to disown Leigh completely.If Turner’s faith in her characters is not always returned — Maria, who gets only one scene, feels underwritten, and Leigh, despite Van Sciver’s foxy performance, never quite coheres — her faith in the audience is an entirely successful investment. Her jokes often have long lead times, the setup in one scene, the payoff in another. The plot, too, keeps well ahead of you, trusting you will survive in pleasurable uncertainty until its loose threads are eventually gathered. In one case, it takes almost 40 pages of script for a throwaway line spoken by the overburdened waiter (Jorge Donoso) to deliver its needle-prick of a reward.That authorial patience is part of what makes “At the Wedding” so fresh; though there are plenty of one-liners, it is not a yuk-yuk comedy foisting its laughs at you or over-signaling its intentions. (“Bull in a China Shop,” Turner’s professional playwriting debut, seen at LCT3 in 2017, was a bit more raucous and insistent.) Also revivifying is the way Turner reshapes the wedding genre for our time, inviting new characters to the party.She does this far too thoughtfully and skillfully for it to seem trendy or polemical. Rather, the broadening is central to the play’s examination of how our traditional ways of uniting people function in a world that has always been more diverse than its institutions.For “At the Wedding,” those institutions include more than just marriage, which many queer people can now choose if they want, in forms that, like Eva’s spectacular gown, are custom fit. They also include love itself, and the loss of it. For Carlo, and for all of us sometimes, love is the albatross strung around our necks, and the sad story we are cursed to tell ever after. It’s funny if it’s not you.At the WeddingThrough April 17 at the Claire Tow Theater, Manhattan; lct.org. Running time: 1 hour 10 minutes. More