After nine movies, several spin-offs, and a handful of TV series, it's difficult to predict where Lucasfilm will go next with Star Wars. The next major movie is currently slated for December 2023, with Rian Johnson, Kevin Feige, and Thor: Love and Thunder director Taika Waititi all set to helm new adventures in a galaxy far, far away. But, for now, we have no idea what any of those movies will be about or when they'll take place.
The previous films have covered a wide range of time — with the Extended Universe going even further into the past — but there's a small sliver within the span of the Skywalker Saga that hasn't made it to the silver screen: the immediate aftermath of Order 66 and the events of Revenge of the Sith. A forgotten comics chapter provides the perfect source material for a future Rogue One-style one-off Star Wars adventure, and it hinges upon the Emperor's brush with death at the height of his power.
Even immediately after purging the galaxy of Jedi, Palpatine had enemies to spare. The Empire was just beginning, and not everyone shared the same ideals as the Sith Lord. So when Palpatine entertained the first graduating class of the Imperial Academies, he shouldn't have been too surprised when the Headmaster of the Raithal Academy decided to take a stand.
As detailed in the non-canon Dark Horse comic Darth Vader and the Ghost Prison, Headmaster Gentis, a General turned academic, disagreed with Palpatine's hawkish ways, even though he knew it would result in a staggering number of casualties, including many of his own sons. In response, Gentis and his students waited until a celebratory gala to stage a coup.
The rebellious cadets set off explosives, and in the chaos, Gentis releases the Aorth-6 virus, killing almost everyone in the throne room. Palpatine survives by using the Force to keep the virus at bay. This use of a bioterrorism weapon is quite rare in the Star Wars universe, so there's an opportunity to blaze a trail here.
Unfortunately, but unsurprisingly, the coup was unsuccessful. Between a freshly-suited Darth Vader and students who stayed loyal to the Empire, this ill-fated rebellion was quashed. Palpatine blasted Gentis and his son with Force lightning until they were nothing but charred corpses, but the effort must have scared Sheev into being wary of rebellion from then on.
This story a vengeful coup would make the perfect plot for a new Star Wars movie in the vein of Rogue One, focusing on a single self-contained adventure rather than another sprawling saga. Plus, just like in Rogue One, we know all the main characters in this movie will die (except Palps, of course).
Just as the newest Batman movie finds a fresh angle showing Bruce Wayne just after he dons the cape and the cowl, Star Wars showing the Empire, itself mere months after its successful coup, almost fall to another coup is a darkly ironic twist between the prequels and the original trilogy. Think of it like Palpatine's Year Two story.
The Empire wasn't built in a day. Showing these learning pains will make the fall of the Empire shown in the original Star Wars trilogy feel that much more believable. After the prequels, it's difficult to see Palpatine as incapable of seeing an attack coming, but seeing him fall, even if he gets some brutal Force lightning revenge on Gentis, would add some interesting nuance to the story of Sheev.