'White House Plumbers' features a stunning twist, but how much of it is true?

There is perhaps no more shocking moment in HBO's Watergate-focused black comedy series “White House Plumbers” than the final seconds of Episode 4 (now streaming). Stop here if you haven’t watched it yet.

As the episode draws to a close, Dorothy Hunt (“Game of Thrones” star Lena Headey), the wife of Watergate burglar (aka plumber) E. Howard Hunt, is about to land at Chicago Midway Airport on a flight from Washington, D.C. On board with her is $10,000 in cash, and a CBS television reporter.

Suddenly, the camera lurches and twists 90 degrees, while Hunt freezes mid-sentence. Then the screen goes black.

That plane, United Airlines Flight 553, really did crash on December 8, 1972, killing two-thirds of its 61 passengers, including Hunt, a congressman and network reporter Michele Clark.

The tragedy immediately ignited conspiracy theories, including one suggesting that the CIA orchestrated the crash. Why? To keep Hunt from revealing what she knew about hush-money payments being funneled from the White House through her family to those involved in the Watergate break-in of the Democratic National Committee headquarters, which led to the resignation of President Richard Nixon in 1974.

We separate fact from fiction surrounding that pivotal tragedy with the help of Garrett Graff, author of the Pulitzer-nominated “Watergate: A New History” and guest on the “White House Plumbers” podcast that accompanies the series.

More: How 'White House Plumbers' Woody Harrelson and Justin Theroux turn Watergate into dark HBO comedy

Was Dorothy Hunt doing a tell-all interview on the plane, as the show suggests?

The episode shows Hunt chatting up Clark, the CBS reporter, and implies she was ready to tell more during and after the flight. Was the cash part of a payoff? All this is most likely pure conjecture aimed at ramping up tension in the series, Graff says.

“She was headed to see the Hunt cousins in Chicago, and the story was that she was taking the $10,000, which was a lot of money in 1972, to have them invest it,” he says.

As for the conversation with the reporter, “I’m unaware of that ever being part of the actual narrative of her real story. That’s creative license they’re taking. Her being on the plane with a reporter and a congressman, as far as I know was all a coincidence, not a conspiracy.”

Was the United flight downed by a government agency to silence Hunt?

A Chicago-based activist and conspiracy theorist, Sherman Skolnick, was one of the most vocal conspiracy theory advocates, and claimed not only that the CIA was involved in the crash, but that Nixon had put a hitman on the flight, who also died.

“Skolnick pieced together various theories indicating there was a larger conspiracy afoot, none of which hold up with more scrutiny,” says Graff.

“Mostly, the evidence from the cockpit voice recorder shows it was a rather mundane crash, that the pilots weren’t paying attention to their air speed, the plane dropped to stall speed, and they screwed up the recovery.”

Did Dorothy Hunt, like her husband E. Howard Hunt, really work for the CIA?

Yes. The Hunts met while stationed in China, says Graff. “He was an intelligence officer and she was agency staff. After his long career, focused largely on South America, they quasi-retired to Washington, D.C.”

Once in the nation’s capital, Howard Hunt focused on his potboiler spy novels while working at an ad agency, a job he secured through his CIA contacts. Dorothy enjoyed a genteel life at a local country club and riding horses.

“Dorothy Hunt did for a while work for the Spanish Embassy in D.C., but it’s debatable if she remained employed then by the CIA,” Graff says.

How much did her sudden death impact the unraveling of the hushed Watergate burglary?

Dorothy Hunt’s sudden death catapults “White House Plumbers” into next week's finale. In real life, “it really was the turning point for much of the Watergate cover-up,” says Graff.

“E. Howard Hunt, at that point, personally unraveled,” he says. “He became embittered and pleads guilty along with five Cubans” who helped with the four different burglary attempts.

Graff says that today, it's a foregone conclusion that the Watergate misdeeds would come to light. “That’s just not true; the cover-up almost worked,” he says.

But then Flight 553 failed to land.

This article originally appeared on USA TODAY: 'White House Plumbers' shocking death: Did it really happen?