Quentin Tarantino is one of the few Hollywood filmmakers who have managed to develop a massive following based on original moviemaking instead of relying on big-name franchises. While talking about his work on Tarantino films dating all the way back to Pulp Fiction, first assistant director William Paul Clark revealed that the third act of Once Upon a Time in Hollywood was kept literally under lock and key during production.

"We kept the third act in a safe in the accounting department. You come, you get the script, you go into the little room, you go read the third act. When you're done, you give the script back, they put it back in the safe and you leave. You take some notes. If you need to refer to something again, you go back. RELATED: Quentin Tarantino Says Burt Reynolds Died Happy After Once Upon a Time in Hollywood Casting

When we got out on location, we just brought a safe and you go to the producer's trailer if you need to read it. The hardest part was getting over the fear of not having the material at your fingertips all the time. Once people got over that fear, it wasn't an issue."

As with all of Tarantino's other films based on historical events, Once Upon a Time in Hollywood makes a sharp departure from the recorded facts to spin a fictional take on real events. The movie tells the story leading up to that fateful night in 1969 Los Angeles when Sharon Tate and her friend were brutally murdered by acolytes acting under orders from Charles Manson.

Instead of showing the murder of Tate and her associates, Quentin Tarantino flipped the script and showed the would-be murderers getting sidetracked and entering the home of next-door neighbor and movie star Rick Dalton instead. Once there, the criminals try to subdue Dalton and his friend/bodyguard Cliff Booth, but are instead beaten up by Booth and his pet dog and burnt alive by Dalton.

It is the kind of unexpected and over-the-top ending only Tarantino could have come up with, and based on what Clark has said, the auteur director was passionately guarded about keeping the third act of his film a secret known only to a select few.

This secretiveness extended beyond the making of the movie. When reporters first began to publish their opinions on the film, Tarantino implored them to avoid giving spoilers to potential viewers. The Wikipedia entry for the movie temporarily had a false ending put in where Bruce Lee foiled the Manson clan's murder attempts in the nick of time.

All this secrecy helped generate a strong buzz, and curious viewers had no choice but to go to the cinemas to see the ending for themselves. As a result, the movie became the second highest-grossing Tarantino feature of all time behind Django Unchained. While there was some controversy regarding the depiction of Bruce Lee as an arrogant braggart, Once Upon a Time in Hollywood has gone on to win many awards and get high ratings on most film review sites.

This news comes from Filmmaker Magazine.