Without question, The Empire Strikes Back doesn't just have one of the biggest shockers in the Star Wars saga, it has one of the greatest reveals in perhaps all of cinema. Back in 1980, when the movie was released, it hit with the force of an atomic bomb, because no one saw it coming. The cast and crew were able to keep it a secret. And the truth never leaked. Surprising, the same can be said about Star Wars: The Last Jedi. It is rumored to have an even bigger surprise. And while some fans have tried to guess, it has yet to be revealed or leaked. Perhaps that's because director Rian Johnson utilized some of the old tricks learned on the set of Empire. How did Mark Hamill and team keep it under wraps the first time around? It wasn't easy, but it was smart.

In a new interview with StarWars.com to celebrate his 66 birthday, Mark Hamill goes on in length about the security measures that played out on the set of Empire Strikes Back. The biggest surprise comes towards the end of the movie. When Darth Vader and Luke Skywalker are having their climatic fight in the wind tunnels of Cloud City. The Sith Lord reveals to the young Jedi in training that his father is not dead. That Vader, is in fact, his real father. It was a moment that made the entire audiences gasp in unison. How did Mark Hamill keep the cat in the bag, as it were? He explains in detail.

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"They kept that line secret: 'I am your father.'" What was in the script was already a fantastic twist. Vader says [in Darth Vader voice], 'You don't know the truth. Obi-Wan killed your father.' And I played it just as you see it. 'No!' and all that. But [prior to shooting] they pulled me aside and [Irvin] Kershner, the director, said, 'Look, I'm going to tell you something. George knows, I know, and when I tell you, you'll be the third person that knows. So if it leaks, we'll know it's you.'"

It's entirely possible this is how Rian Johnson, Mark Hamill and Daisy Ridley kept a lid on it this time around, as well. Though, who's to say they are the keeper of such a big secret in this sequel? The huge reveal promised at the end of Last Jedi could potentially involve any number of actors, from Kylo Ren, to Snoke to even Finn and General Leia. Whatever they know, perhaps they are the only ones who know it, while the rest of the cast and crew have been kept in the dark?

Earlier in the year, a Japanese pamphlet for The Last Jedi leaked. And it's notorious for declaring that Star Wars 8 will have the biggest reveal of any Star Wars movie to date. Yes, it promises to trump even Darth Vader being revealed as Luke and Leia's dad. Translated, the official piece of tie-in literature says this.

"The Most Shocking Truth In Star Wars History Will Soon Be Revealed! A new generation's tale of the struggles of light and dark, virtue and evil has begun with the death of Han Solo. In a Galaxy where First Order and the Resistance are fighting against each other in a war, the heroine, Rey, had the Force awaken within her. What will happen to the galaxy when Rey and the only remaining Jedi knight, Luke Skywalker, meet? Kylo Ren has fallen to the Dark Side of the Force and killed his father, Han Solo. As a successor of his grandfather, Darth Vader, and a high ranking enforcer in the First Order, where will his ambition lead him to? Furthermore, Kylo Ren's mother, the leader of the Resistance, Leia, Poe, Finn, and BB-8, will embark on a new mission! The story has finally begun and it will lead to a mysterious climax! December 15. Be ready for the shocking truth surpassing the previous stories!"

We've come a long way. And the secret hasn't been spoiled yet. Sure, there has been plenty of speculation. But nothing has been substantiated or confirmed by Lucasfilm. The cast and crew are doing a terrific job of keeping it all under their hats for the time being. But the answers will arrive soon enough, with the movie in theaters this December.