As the first act of Arthur Miller's All My Sons nears its climax, the atmosphere is thick with tension and discomfort. A young man has proposed to the former girlfriend of his older brother, presumed dead three years after World War II. The boys' mother, convinced that her child is still alive, is on the edge of a nervous breakdown. The boys' father, obviously hiding some dark secret, appears deeply nervous about an incoming phone call. And in St. Ambrose University's Saturday-night production of this American tragedy, you could tell that its Act I closer was really working, because for a few brief minutes, the audience collectively stopped coughing.