This article contains spoilers for Star Wars: The Last Jedi.

Star Wars is a unique place right now, in terms of the franchise’s history. Until now, it has always been about a single story — the thread that’s told through the movies or the TV shows. Sure, there’s a whole universe out there of books that came out before Disney’s purchase of Lucasfilm, but they weren’t trying to tell stories at the same time. The movies and Expanded Universe have always been separate in terms of when they were telling stories. After all, the Thrawn trilogy wasn’t released until the early 1990s.

It’s well known at this point that George Lucas didn’t consider the novels canon. When Disney purchased Lucasfilm, they turned the the old stories into “Legends” and began issuing new books to go along with the films they were releasing. It made sense; they couldn’t tell new stories if everything had already been written. As a result, the company is now balancing publishing comics, novels, TV, and movies that overlap and intertwine in myriad ways. Often gaps in the movies are filled within pages of another tome.

Want to know how Poe Dameron tracked down Lor San Tekka (played by Max von Sydow) in The Force Awakens? Read the Poe Dameron comic. Interested in what happened when Saw Gerrera abandoned Jyn Erso? Check out Beth Revis’ Rebel Rising. Frustrated that the origins of Snoke weren’t revealed in The Last Jedi? Don’t worry, it will probably be covered in a book at some point (assuming the movies are finished with him).

Being able to tell a larger story than just a two-hour movie will allow is one of the great things about Star Wars. It allows those who want to to really get into the trenches, to dive into the nitty-gritty of theorizing and trying to figure out what everything means.

The problem, though, is when it starts feeling like the movies are leaning on the Expanded Universe a little too hard, when it starts seeming like you have to read the books and the comics to understand what you’re seeing on the screen. The bottom line is that if a movie can’t tell an effective story, with understandable and relatable plotting and character development without additional material to prop it up and explain what happens, it fails at storytelling. Star Wars is getting dangerously close to that precipice.

Nowhere is that more clear than the fundamental conflict at the center of the current trilogy: the battle between the Resistance and the First Order. Every time I talk about the Star Wars movies with someone who isn’t immersed in the current canon, I get the same questions: What is the First Order? Where did it come from? What is its relationship to the Empire? What is the Republic? What is its relationship to the former Republic? Why is there a Resistance when there is a Republic? What’s the relationship between the Republic and the First Order?

Now, I can begin to answer these questions because I’ve read books like Bloodline by Claudia Gray and Chuck Wendig’s Aftermath trilogy. While there hasn’t been a lot of information, there’s enough to be able to start putting all the pieces together.

But the fact that even the basics of these questions haven’t been addressed in the movies is hard to justify. “Well, that’s explained in the books,” is an incredibly weak argument. It’s not like this is information that piques curiosity but isn’t actually central to the story that Star Wars is trying to tell -- like Snoke’s origin story or the founding of Luke’s Jedi Academy. While those are certainly interesting, and I hope they are addressed in a novelization or comic somewhere, they're not critical to understand what’s happening on the screen. However, the relationship between the Republic, the First Order, and the Resistance is crucial to the plot.

The hard part is, as Star Wars grows larger and larger, this problem is just getting worse. It’s going to become more difficult to tell a self-contained story set within this larger universe without assuming the audience has a fluency with its nooks and crannies. The people at Lucasfilm are talented, and I’m sure they’re working on it. But the lack of explanation of the First Order/Resistance/Republic politics on the screen has me worried, and I hope it’s not a harbinger of things to come. I never want Star Wars to use the Expanded Universe as a storytelling crutch, and therefore become less accessible to casual fans.

The fact is, a two- to three-hour movie can’t explain everything in a universe as big as Star Wars, and it shouldn’t try. People should certainly leave the theater with questions about the bigger picture, and it’s a good thing when that curiosity drives them to pick up a book or a comic or start watching one of the TV shows. But that should never be because of a failure of storytelling. No one should be required to engage with the Expanded Universe in order to understand what’s happening on the big screen.