There have been tipping points and bombshells, walls closing in and turning points. And there have been so, so many declarations of “The beginning of the end!” that the comedian John Oliver had a recurring, satirical “We got him!” segment on his late-night HBO show, complete with a jubilant marching band and sequined majorettes celebrating President Trump’s downfall.

But in the swirl of reporting and speculation about the 45th president, nothing has held viewers on the edge of their seats quite like the special counsel, Robert S. Mueller III, and his investigation into possible ties between Mr. Trump’s 2016 campaign and Russian agents.

The story line had it all: Cold War-era intrigue, allegations of shadowy meetings in Moscow and a cast of recurring characters that included an aide in a $15,000 ostrich skin jacket (Paul D. Manafort) and another who has a tattoo of Richard Nixon on his back (Roger Stone).

Mr. Mueller’s complete report hasn’t yet been released, but on Sunday, Attorney General William P. Barr made public a four-page letter to Congress reporting that the 22-month inquiry did not have sufficient evidence to conclude that Mr. Trump and his associates “conspired or coordinated with the Russian government” ahead of the 2016 election. The news blindsided many liberals — particularly those with an ambient knowledge of Rachel Maddow’s nightly monologues on MSNBC.