Indiana Jones is undoubtedly one of the most popular film franchises ever made. With Raiders of the Lost Ark, Steven Spielberg, Harrison Ford, and George Lucas crafted an iconic character for the ages, and so when it was announced earlier this year that Indiana Jones 5 is officially in the works, with Ford starring and Spielberg directing, fans were enthused to hear that Indy would be returning for yet another go-around over 30 years after Raiders first hit theaters.

Disney and Lucasfilm subsequently announced that screenwriter David Koepp, who collaborated with Spielberg on Jurassic Park, War of the Worlds, and yes Indiana Jones and the Kingdom of the Crystal Skull, would be handling scripting duties for Indiana Jones 5, and so when Collider’s own Steve Weintraub recently spoke with Koepp for an exclusive interview in anticipation of the release of Inferno (which Koepp wrote), the conversation obviously turned to Indy 5.

Koepp said he’s hard at work on writing the script for Indiana Jones 5, but one big question that loomed over the film was whether Lucas would be involved. The way the franchise worked in that past was that Lucas would come up with the idea for the movie and Spielberg would execute it. When Indy 5 was announced, Lucas’ name was nowhere to be found. Spielberg subsequently said Lucas would serve as an executive producer on the film, but in speaking with Koepp, the screenwriter revealed that Lucas is not involved in the story of Indiana Jones 5:

“He’s not, to my knowledge. I’ve had no contact with him.”

That’s certainly a curious revelation, as it marks a first for the franchise. Some may find this development promising as it was Lucas’s insistence that Indiana Jones 4 tackle the concept of aliens in the 1950s setting that made the film so tough to crack. Indeed, a number of screenwriters worked on the Last Crusade follow-up before the script was in a place that made Spielberg, Lucas, and Ford all happy, and thus Indiana Jones and the Kingdom of the Crystal Skull was born.

As the credited screenwriter on Crystal Skull, Steve asked Koepp what he thinks they learned from that film that may have informed the approach they’re taking for Indiana Jones 5. As it turns out, it’s all about the MacGuffin:

“I think that what [Indy] looks for and when he looks for it dictates what the movie’s gonna be. So the selection of the MacGuffin is everything. I think Kingdom of the Crystal Skull, being set in 1957 there was a conscious desire to say, ‘Much like two of the other ones were World War II movies set in the 30s and early 40s, this is ’57 so a lot of our influences are gonna be science-fiction movies.’ You got that with the original [script], Jeb Stuart took the first shot at it with Indiana Jones and the Saucer Men from Mars. That was a really conscious decision that dictated a lot about what the story would be and what the movie would be like, and I think that was followed through on really nicely. I thought Steve did a really good job with that. I don’t know that the idea was most suited to an Indiana Jones movie, but that was what we did. So we tried to be very careful with the selection of the MacGuffin and the eras to give ourselves as much latitude to make the best kind of Indiana Jones movie that we most want to see. Learning how that’s the importance of the choice of the MacGuffin is a big deal.”

As for what else Koepp learned from Crystal Skull, he noted that not repeating past mistakes is obvious, but reiterated that they really focused on the MacGuffin—i.e. what Indy is trying to get—this time around and making sure that fit with what kind of Indiana Jones movie they wanted to make: