LOS ANGELES — Have you heard the one about the moon landing?

Not that it was staged. We all know that rumor is a bunch of bunk.

No, this story involves what Neil Armstrong and Buzz Aldrin were doing during those 21 minutes of radio and video silence on the Apollo 11 mission.

You think they were turning over rocks and drinking Tang? Think again. Turns out the two astronauts were actually bouncing over to the dark side of the moon, investigating a crashed alien space ship that turned out to be — yes — a massive Transformer robot.

“We give you a whole new reason why the moon landing actually did happen,” Lorenzo di Bonaventura, producer of the “Transformers” movies, says. “Everyone was right. The conspiracy existed. It was just a different one than people thought.”

Conspiracy theories are the rage these days, and not just the intrigues spread by the likes of Glenn Beck, talk radio hosts and the guy who sees mystery in Taco Bell’s “seasoned ground beef.”

There are even loopy theories surrounding conspiracy-tinged material that has been adapted to the screen. Did Stieg Larsson really write the best-selling series of thrillers, which, beginning with “The Girl with the Dragon Tattoo,” were published after his early death by heart attack? And was his death natural or was he murdered by neo-Nazis?

So all this code-red anxiety in the air has begun to permeate the multiplex as filmmakers proffer plots and plans and secrecy, the likes of which haven’t been seen since agents Mulder and Scully poked around Area 51 in “X-Files.”

“Transformers: Dark of the Moon,” due out June 29, uses the Apollo 11 lunar mission to accomplish something that sounds entirely implausible — namely, give a “Transformers” movie an actual storyline.

Dimension Films, meanwhile, has “Apollo 18” (due January 2012), a horror film that claims to be found footage from a secret lunar expedition that the government covered up because alien monsters ate the astronauts.

There are also conspiracy movies that sport some historical documentation. Robert Redford’s “The Conspirator,” opening Friday, contains not one, but two plots — the first involves Abraham Lincoln’s assassination, the second, the government’s efforts to try the assassins and anyone connected to them without regard to their constitutional rights.

And this fall, director Roland Emmerich (“Independence Day,” “2012″) sets aside cataclysmic disasters and end-of-days Mayan prophecies to focus on the authorship of the works credited to William Shakespeare in “Anonymous.” Guess what? Shakespeare didn’t write them.

The imminent arrival of all these movies — in addition to the currently playing “Source Code,” a thriller revolving around yet another secret government program — prompts some reminiscing about post-Watergate conspiracy thrillers like “Three Days of the Condor” and “The Parallax View,” movies that arrived during a similar era of unrest.

“When the world gets complicated and people start feeling at a loss, these types of conspiracy stories start showing up in pop culture,” says USC professor Leo Braudy, who has written several books on film.

“Pop culture is designed to upset you and give you solace,” Braudy said. “The possible existence of a conspiracy would be upsetting. But it’s solacing, too, because at least somebody knows what’s going on. The problem is, of course, that the real world is chaotic and maybe no one knows what’s going on.”

Adds Chip Berlet, who studies conspiracy culture for Political Research Associates, a Boston-based think tank: “Between the collapse of the economy and unresolved fear after 9-11, there’s a lot of anxiety that has to be expressed some way. People don’t believe their leaders are telling the truth and they look for alternate explanations.”

And that, of course, would include the leaders of the nation’s space agency, with conspiracy theorists spinning tales of NASA-lead hoaxes from the time Armstrong took one giant leap for mankind in 1969.

The 1978 movie “Capricorn One” took that lunar intrigue, added a dash of post-Watergate, anti-Washington outrage and spun a tale of a fake Mars landing that turns into a murderous, government cover-up.

The new “Transformers” movie and “Apollo 18” add to the lunar conspiracy legacy.

“With moon conspiracies, there’s a contradiction at work,” di Bonaventura says. “There’s a deep-seated romanticism about the moon with the poetry and romantic settings. Then you have this notion that there’s this gigantic lie propagated about what may be 20th century man’s greatest single achievement.”

Military legal historian Fred Borch, who acted as chief prosecutor of the Guantanamo military commissions and worked as an advisor on Redford’s “The Conspirator,” believes such notions, however far-fetched, will never go away.

“As a people, we Americans seem to be distrustful of official explanations,” Borch says. “It goes back to our character, historically, dating from our own revolution in the 1770s. Americans have always been rather distrustful of government.”

The problem, Berlet says, is not that Hollywood feeds this mistrust but that political, business and religious leaders don’t step up and address the underlying problems that stoke conspiracy theories in the first place.

“In a healthy society, people would be rolling their eyes at this stuff,” Berlet says. “But nowadays, no matter how far-fetched the rumor is, people say, ‘Hmmm. maybe there is something to that.’”