"Based on a true story" the movie's blurb reads. Well, there is based on and there is" true to". No movie is going to get it 100 percent right. And sometimes a movie gets the history right, but maybe deviates from the actual story. And it's true to say that some movies are more accurate than others. Take an iconic film like The Sound of Music. It makes the Reader's Digest list of the most inaccurate movies of all time.

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Why? Just one example will do: When the movie family escapes from the Nazis, they go trekking over the Alps. In reality, they walked into Italy across a railroad track. Simple as that. Here are 10 movies that do a pretty good job of being accurate to the "true story".

127 Hours (2010)

Gritty director Danny Boyle served up the story a one Aron Ralston who was alone and wedged between a boulder and a canyon wall. He was stuck. So, over 127 hours he comes to grips with his situation. His only option is to hack off his arm. Try sitting and watching that scene.

The movie was true to the actual event, down to getting Ralston's psychological struggle and his desperation down pat. Ralston has said that the movie is “so factually accurate it is as close to a documentary as you can get and still be a drama.”

Zodiac (2007)

In the late 60s and early 70s, a serial killer dubbed "The Zodiac Killer" stalked and terrorized the San Francisco Bay area. He was never caught. A journalist by the name of Robert Graysmith (played by Jake Gyllenhaal) became obsessed with the case. In 1986, he wrote a book of the same name on which the film is based. The filmmakers conducted extensive interviews, went over case files and were on a mission to be as true to the story as possible.

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They succeeded. And they made a very good film to boot. Robert Downey Jr. is Paul Avery, a journalist noted for his reporting of the case.

A Night To Remember (1958)

Forget the 1997 film Titanic as far as accuracy goes, A Night to Remember is largely regarded as the of all the most accurate of all the Titanic films. Firstly, it was based on a historian's researched account of the 1912 sinking of the Titanic. Secondly, the filmmakers recruited actors who resembled the actual passengers. And thirdly, they lovingly and accurately recreated the ship's interiors.

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Sure, there is some dramatic license taken, but the movie usually sticks to the facts.

Apollo 13 (1995)

The story of the Apollo 13, the failed 1970 lunar mission was brought to life by director Ron Howard. Of the movie, astronaut Dave Scott has gone on record saying it is "a source of accurate data". In fact, he advised Howard on the film. Howard studied video footage and transcripts in an effort to be as accurate as cinematically possible.

Of course, he throws in some drama that never happened. But the look of the capsule, even some of the lines, come straight from the real thing.

All The President's Men (1976)

Robert Redford and Dustin Hoffman are Bob Woodward and Carl Bernstein, the doggedly determined Washington Post reporters who helped uncover the truth behind the NixonnWhitehouse's part in the Watergate Conspiracy. Redford and Hoffman spent time with Woodward and Bernstein and the director Alan J. Pakula insisted on an accurate rendering of the newsroom in which the reporters worked.

The film is a good one, but because it is true to the drudgery of investigative journalism, it can be a bit slow at times.

Spotlight (2015)

Another investigative journalism movie, director Tom McCarthy's story of the Boston Globe's dogged investigation into the Catholic Church's sweeping sexual abuse by priests under the proverbial carpet focuses on the course of the investigation itself. Of course, it is broad-brush in places, but the course of the investigation and the dynamics between editor Walter Robinson (Michael Keaton) and his reporters ring true

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As in the real investigation, the eureka moment comes when a researcher throws in the idea that, instead of the 20 or 30 priests they are limiting their investigation to,  the paper needs to look for a "significantly higher" number of possibly- abusive priests. Said a former Globe "it gets a lot right".reporter,

The Grey Zone (2001)

Two characters in The Grey Zone

The Grey Zone is hard to watch some of the time. It tells the story of the Sonderkommandos, Jewish prisoners at Auschwitz whose job it was to recover dead bodies from the gas chambers at the camp during World War II. Says Roger Ebert "I have seen a lot of films about the Holocaust, but I have never seen one so immediate, unblinking and painful in its materials."

The film's more grisly scenes have sometimes been criticized, but are a fairly accurate portrayal of what went on. It is hard to take at times. But it seems very real.

12 Years A Slave (2013)

The tail of Solomon Northup, a free black man from New York who is abducted and sold into slavery is a gripping tale of loss and survival, against all the odds. It is based on Northup's 1853 autobiography. And, ignoring boring details about cotton farming, it is true to the overview of his story. But it takes a broader view and is true to the real horror of slavery in the Old South, its brutality and inhumanity.

So, it is accurate from Northup's story point of view and accurate from a historical perspective on slavery.

Selma (2014)

The Guardian gave Selma an "A" for its history. The movie, of course, tells the story of Dr. Martin Luther King Jr. and the 1965 Selma to Montgomery (the Alabama State Capital) Civil Rights march. It also tells the story of the dynamic between King and President Lyndon B. Johnson. King wants to push forward with voting rights. Johnson wanted to attack poverty.

The film gets the historical detail of the march spot on and Tom Wilkerson is so good as Johnson that it is a little scary. Like 12 Years a Slave, Selma good history, as well as a faithful rendering of the story.

Catch Me If You Can (2002)

Frank Abagnale will go down in the annals of crime as one of the greats. He was multi-talented, turning his hand to cons, forging, and just pretending to be somebody he wasn't.  Put him in a pilot's uniform and he is co-piloting a plane for Pan Am. He had a turn at being a resident in a hospital, practicing law and being a college sociology professor. All without knowing anything about the job at hand.

Based on Abagnale's book of the same name and starring Leonardo DiCaprio, the movie stays true to the book and captures both the cheeky spirit of a true con man and the broad brush story and follows Abagnale from living life on the lam, to forming his own security firm to protect institutions from people like him.