“If I win, I am going to instruct my Attorney General to get a special prosecutor to look into your situation,” Trump said. “Because there has never been so many lies, so much deception. There has never been anything like it, and we’re going to have a special prosecutor.” He had now turned toward Clinton, and was shaking his finger at her; at various points during the evening, which was set up as a town-hall meeting, he had paced behind her when she walked over to talk to audience members, shadowing her with all the subtlety of one of the agents in “Spy vs. Spy.” At times, the oddness of their dance in that small space, and the unrestrained ugliness of Trump’s attacks, meant that it didn’t seem ridiculous to wonder if they might, actually, start shoving each other. But after he mentioned a special prosecutor, Clinton laughed. She knows all about special prosecutors, after all. The one Trump wanted would be for her e-mail, but there had been a number of them looking into all manner of things in her husband’s Administration—including some of the stories of the women Trump had brought with him—and she had made it through that. As Trump talked about the e-mails, and how she had used an “acid wash” on them, and said, for the second time, that she “should be ashamed,” she stood up and composed her expression with a calm, pitying smile.

Martha Raddatz, the moderator, began to ask a follow-up, but Clinton interrupted her. “Let me just say, because everything he just said is absolutely false . . .”

“Oh, really?” Trump interrupted.

“I’m not surprised,” Clinton continued, and explained that, given the number of lies Trump told, she would never get to talk about her actual policies if she spent all her time “fact-checking Donald.” (That is a fair statement.) She mentioned a fact-checking hub on her Web site, and then said, “It’s just awfully good that someone with the temperament of Donald Trump is not in charge of the law in our country.”