As part of our ongoing celebration of all things Star Wars, the next few weeks will see Tor.com contributors writing about Timothy Zahn’s game-changing “Thrawn Trilogy,” a book series that arguably revitalized, and reivented Star Wars forever. From Coruscant to clones, it’s hard to imagine living in a Star Wars universe without these novels!

First up, was Heir to the Empire the moment when Star Wars veered more towards hard science fiction?

In the summer of 1992, an eleven-year-old me would ride his lime-green bicycle to the steps of the Dobson Ranch Library in Mesa, Arizona, hoping each time to see if his name had advanced on the waiting list to read Heir to the Empire. And when it finally did, and I began tearing through the pages, I remember feeling a little weird. I loved it, of course, but looking back, the reason Zahn’s first Star Wars novel is so wonderfully odd is that it audaciously asserts Star Wars not as epic space fantasy, but instead, science fiction.

MILD Spoilers for Heir to the Empire

The 80’s and early 90’s were not filled with a preponderance of Star Wars junk, at least not by today’s standards. Back then, a new Star Wars comic book or novel felt important and special, with the Zahn trilogy being the most legit Star Wars thing of all. Kids playing on the playground didn’t know the “expanded universe” didn’t really count, because at that time the Star Wars universe was still expanding. As far as we were all concerned Heir to the Empire was the totally real-deal sequel to Return of the Jedi. Just look at the cover! It looks like one of the movie posters! And there’s some dude shooting lightning/lasers out of his fingers! Yeah, I’m pretty sure that’s real Star Wars.

And yet, here’s a pre-Phantom Menace Star Wars story rendering the Force as a science fiction concept instead of a mystical catch-all religion. Zahn’s invention of the ysalamiri—creepy little slugs who negate the Force—is the move of an author trying to make some science fictional sense of this wacky fantasy world. Much of this first novel in what many later call the “Thrawn Trilogy” concerns the machinations of one Grand Admiral Thrawn and his complicated scheme to get the Empire back on its feet. Correctly, Zahn made his titular Heir to the Empire an alien, a blue-skinned, red-eyed Chiss who doesn’t randomly kill off his subordinates. And though my youngling self read Dune after reading Heir to the Empire, there’s something decidedly reminiscent of Dune in Thrawn’s conception of how to take over the galaxy. The Force is a commodity Thrawn knows he needs to control in order to show everyone he’s the boss. In this way, the ysalamiri are more than just Jedi-kryptonite, they’re actually one piece in a larger big-bad-guy plan.

Which brings us to Joruus C’Baoth, an insane Dark Jedi clone of a Jedi named Jorus (one “u”) C’Baoth. Wait? Clones? You mean when a person’s DNA is taken to create an identical copy that person? Despite mentioning “The Clone Wars” in A New Hope, the Star Wars universe, at this point, had not actually depicted the science fiction applications of clones and cloning. But after Heir to the Empire, Zahn firmly asserted bona fide clones as part of Star Wars, and you could argue this fictional universe was never the same as a result. As far as the novel and Thrawn’s schemes go, Joruus is another component in the plan to make sure elements of the Force are firmly on the side of darkness. Instead of characters who use the Force as the main players, Heir to the Empire depicts a galaxy full of non-Force users who are totally freaked out by the Jedi and their ilk. And yes, while Luke and Leia are integral to the story, one gets the sense that the galaxy is reacting to their presence, in a very real, and political manner. This too, gives the novel more of a feeling of hard science fiction, if only because it speculates on how “normal people” (whether they are furry Bothans or blue-skinned Chiss) would really handle folks who can levitate stuff with their minds.

And what about our beloved Star Wars characters from the original trilogy? It’s here where Zahn split the difference between turning Star Wars in to a science fiction novel full of space politics, ensuring the book was still full of Star Wars stuff. Everyone seems in character, but what’s most wonderful about Heir to the Empire is that it’s truly the first time the culture experienced Luke, Han, Leia, Lando and everyone else not in opposition to Darth Vader and the Emperor. In so many ways, the characters of the films are fairly thin, archetypal people, more defined by what they are doing, rather than who they are. But here, Luke has to cope with Obi-Wan’s ghost saying goodbye forever, Leia is becoming a mother and a Jedi at the same time. Lando is still trying to make a living, and Han is struggling to apply his devil-may-care attitudes to a more civilized lifestyle. Everything the main characters get to do is exciting and feels like Star Wars (Luke getting stranded in his X-Wing in deep space is particularly memorable and deliciously Apollo 13-esque), but Zahn correctly realized these people needed new and dynamic characters to challenge them, which is why he invented not just Thrawn, but Talon Karrde, and Mara Jade too. These aren’t evil laughing assholes in black capes and cloaks. The foils for the Star Wars heroes in Heir to the Empire are fully realized, and interesting people.

Star Wars is infamously lacking in female humans not named Princess Leia, a fact corrected by the introduction of Mara Jade in Heir to the Empire. Putting Mara on both sides of the law is also a good move, as it immediately disqualifies her from damsel-in-distress status. Further, Mara Jade is probably the best ticking time bomb character in all of Star Wars, simply because she’s been programmed with one very serious order: Kill Luke Skywalker! Finally, thrusting Luke and Mara together toward the end of the book is also a fantastic and classic device. I always like a book where you can say “they’re not out of the woods yet!” when the characters are literally still in the woods.

While Heir to the Empire ends on perhaps a less-satisfying cliffhanger than “I am your father,” it does adhere to its own rules and tonal qualities. With this groundbreaking Star Wars novel, Timothy Zahn asked the question: “what if I wrote Star Wars as serious SF? What would that be like?” And the answer was: totally awesome, enthralling, and best of all, new.

Ryan Britt is a staff writer at Tor.com.