Mr. Mueller might issue a report in 2019 that concocts a confection of guilt by innuendo based on the Russia-related dealings and statements of Mr. Trump and the people around him. Alternatively, he could clear the air: Mr. Trump’s election was the doing of the American voter and nobody else.

But it’s already pretty obvious that he’s not going to tell us anything that will greatly shift our understanding of the 2016 race. Whereas, in the still-classified appendix of the Justice Department inspector general’s report on Mr. Comey’s actions are the beginnings of an untold and important story: how U.S. intelligence agencies, using Russia as an excuse, fiddled ineptly and improperly in our election and quite conceivably undermined the Hillary victory they were so obviously trying to secure.