Tonight is your last chance to catch local playwright Holly Arsenault’s debut, Undo. The premise is so simple and brilliant—what if a divorce were a public event precisely like your wedding, with guests and presents and an officiant and tons of booze?—that it threatens to overpower the show itself. But Arsenault’s sharp wit and ear for honest dialogue, which focuses on realistically mundane details and then telescopes to huge family drama, makes the concept work beautifully. Bring someone to talk it over with after; you’ll surely want to. (Annex Theater, 1100 E Pike St,, 8 pm, $18 adv/$20 DOS)