BackStage Theatre Company's ingenious, exuberant revival of Thornton Wilder's 1942 saga is a tonic and a triumph. Because the story spans a period from the dawn of time through World War II, the stage must be transformed into a New Jersey bungalow beset by a wall of ice, a 1929 Atlantic City beauty pageant that succumbs to Noah's flood, and a painfully contemporary war scene. Over nearly three hours, director Brandon Bruce's 16-member cast seldom strikes a false note or misses Wilder's trenchant wisdom, treating period ballads, clever sight gags, and deft caricatures with inexhaustible high spirits. As Sabina, the predatory maid-narrator who deeply distrusts the play, Rebekah Ward-Hays exemplifies Wilder's cunning, constantly surprising us. Through 4/2: Thu-Sat 8 PM, Sun 3 PM, Chopin Theatre, 1543 W. Division, 312-683-5347, $12-$15.