In 2020, one hitherto unknown report accurately predicted what was to follow Biden’s election. It also laid out a plan to preserve democracy in an uncertain future. Weeks before the 2020 election, a secret 87-page document outlined in matter-of-fact language the threat posed by Donald Trump’s still-to-come campaign of election denial. The private paper — the existence of which has not been reported before — forecast with chilling confidence the likelihood of violence during the presidential handover and proposed a far-reaching set of political reforms to thwart Trumpism in the future. Americans remember that dark winter well. But the impetus...