The classic definition of chutzpah — the guy who murders his parents and then begs for mercy because he’s an orphan — is getting a rewrite with the Oct. 16 release of “Truth,” a movie that insists forged documents are real.

Robert Redford, who makes no effort whatsoever to look or sound like Dan Rather, plays the CBS newsman undone after he presented to the public obviously forged documents about then-President George W. Bush’s Texas Air National Guard service in the early 1970s.

It was September 2004, two months before Bush was to be re-elected in a tight race against Vietnam veteran John Kerry, and Rather’s “60 Minutes II” producer Mary Mapes (played by Cate Blanchett with her usual brittle intensity) is desperate for a scoop.

She and her team of researchers (Dennis Quaid, Topher Grace and Elisabeth Moss) set out to find information damaging to the president, methodically contacting everyone they can think of in the chain of command during Bush’s National Guard days to find some dirt on him. (In one unintentionally revealing moment in the film, co-written and directed by “The Amazing Spider-Man” scribe James Vanderbilt, Mapes is shown watching a TV commercial paid for by the Swift Boat Veterans for Truth, an ad hoc group formed by Kerry’s former colleagues in the Navy. She shows a complete lack of interest in digging into their stories. In fact, in the summer of 2004, the mainstream media almost completely ignored the Swift Boat veterans, as the ad campaign did serious damage to Kerry’s reputation.)

Mapes found a squirrely retired National Guard colonel named Bill Burkett, who gave her photocopied memos that purported to show Bush had been AWOL for a significant portion of his National Guard tenure. The font and spacing on the memos perfectly matched the default settings on a 21st-century Microsoft Word program, Burkett kept changing his story about how he got the documents until he sounded completely insane (and Blanchett is shown making the “cuckoo” sign as she listens to him), two of CBS’s own document experts raised doubts about them — and Burkett was a Bush hater who agreed to hand over the documents in the first place on the condition that Mapes put him in touch with the John Kerry campaign, which he wanted to assist. Mapes and Rather ran with the story anyway, defending it for days — even after other media organizations began casting doubt on them.

“Truth” makes it appear that the documents’ contents were verified by a senior officer in Bush’s unit, Gen. Bobby Hodges. Mapes is seen reading the documents over the phone to him, and Hodges agrees that they accurately reflected the mindset of Bush’s late commander, Lt. Col. Jerry Killian, whose signature is on the documents.

That, in reality, did not happen — at least according to Hodges: He was not told that the accuracy of the documents was in dispute, and essentially said, “If Killian wrote that, that’s what he felt,” noted Megan McArdle (an Obama voter) in an analysis of the case on Bloomberg View. Hodges took extensive notes of the interview at the time, and some of the things Mapes would claim they discussed did not turn up in his version of the chat. (In the movie, Hodges is later shown objecting to being described in the media as Mapes’ trump card — but doesn’t deny having provided backing to Mapes’ story.)

In the film’s most climactic scene, Blanchett is forced to explain herself to a CBS-appointed fact-finding committee headed by Dick Thornburgh, who had served as attorney general under the first President Bush. She gives an impassioned defense of her work in a speech meant to make the audience stand up and cheer — but instead comes across as obtuse to the point of being self-delusional.

Blanchett’s Mapes tells the committee that the documents had to be genuine because they contain military acronyms and jargon and show knowledge of Bush’s military service (which had been extensively covered in the media). It beggars belief, she claims, that anyone could go through so much trouble and then produce fake documents using Microsoft Word. She even insists she’s been persecuted for her political leanings (though she won’t admit to any): “You mean, am I now or have I ever been a liberal?” she asks the committee. At one point she declares, “Our story was about whether the president fulfilled his service. Nobody wants to talk about that. They want to talk about fonts and forgeries, and they hope to God the truth gets lost in the scrum!” Except Mapes couldn’t prove the president went AWOL without the documents.

Eight people, including Mapes, Rather and three CBS execs, lost their jobs over the scandal. As Kevin Drum wrote in Washington Monthly after the committee report was released, “It’s a train wreck. A complete disaster. You have to read the whole report to get the full flavor, but the nickel version is simple: It’s unbelievable that this ‘60 Minutes’ segment ever got on the air.”

Another climactic moment near the end comes when Topher Grace’s researcher character, having been fired by CBS, gives a similarly long and angry speech about how CBS and its then-corporate owner Viacom are simply doing the handiwork of its allies in the Bush administration because of Viacom’s interests involving FCC rules.

That speech is equally nutty: It raises the question of why CBS would have allowed the story — or any other anti-Bush stories — to run in the first place. Mapes won a Peabody for her reporting that same year on the Abu Ghraib scandal.

“Truth” is based on Mapes’ memoir, “Truth and Duty: The Press, the President, and the Privilege of Power.” Mapes, who hasn’t worked in TV news since the scandal, and Rather insist to this day they were right, and Rather even sued CBS for breach of contract. The lawsuit was laughed out of court — in much the same way that “Truth” will be laughed out of theaters.