Five days after Donald Trump was elected president, Alex Halderman was on a United Airlines flight from Newark to Los Angeles when he received an urgent email. A respected computer scientist and leading critic of security flaws in America’s voting machines, Halderman was anxious to determine whether there had been foul play during the election. Had machines in Wisconsin or Michigan been hacked? Could faulty software or malfunctioning equipment have skewed the results in Pennsylvania? “Before the election, I had been saying I really, really hope there’s not a hack and that it’s not close,” he says. “Afterwards, I thought, ‘Wait a minute, there’s enough reason here to be concerned.’ ” Now, wedged into a middle seat on the cross-country flight, Halderman stared in disbelief at the email from Barbara Simons, a fellow computer scientist and security expert. Working with Amy Rao, a Silicon Valley CEO and major Democratic fundraiser, Simons had arranged a conference call with John Podesta, Hillary Clinton’s campaign chair, to make the case for taking a closer look at the election results. Could Halderman be on the call in 15 minutes? United’s wi-fi system didn’t allow for in-flight phone calls. But Halderman wasn’t fazed. “I’m blocked,” he emailed Simons, “but I can try.” Within minutes, Halderman had circumvented the wi-fi and established an interface with computers at the University of Michigan, where at 36 he is the youngest full professor in the history of the computer science department. He dialed in to the call but did not speak, afraid of drawing attention to the fact that he was violating the airline’s phone ban.