Star Trek: Discovery has finally confirmed one of the show’s longest running theories in the latest episode, “Vaunting Ambition,” when Michael Burnham came to the horrifying realization that her captain, Gabriel Lorca, has been from the Mirror Universe all along. Mirror Lorca has seemingly orchestrated the events of the entire series up to this point to overthrow the Terran Empire’s ruler, Philippa Georgiou.

Burnham comes to the realization while discussing a trade with Emperor Georgiou, who wants access to the Discovery’s spore drive schematics in exchange for helping the crew return to their universe. Georgiou explains to Burnham that Lorca is obsessed with her, and was both a father figure and possible lover to Mirror Burnham (further confirming the inherent ickiness of the parallel reality).

As Burnham begins to realize that Lorca has almost identical traits to the Mirror version Georgiou describes, she gets the last bit of confirmation she needs: Georgiou suffers from the same optical ailment as Lorca, which she confirms is a condition native to Mirror Universe humans. Lorca, tortured by the brother of one of crew members of the destroyed ISS Buran, confirms his identity when he names the officer’s sister before brutally killing him.

This has been a long-standing fan theory about Lorca, who is a decidedly more reckless and amoral captain than we’re used to seeing in Star Trek shows. This had been mostly waved away as simply the effects of a long, brutal war on a flawed man, but the truth turns out to be a much different matter altogether. This, more than any of the show’s other much-debated plot twists, is a genuine game-changer; Burnham may be the show’s central character, but in many ways Lorca has defined both her world and the worldview of the show itself. It’s hard to see how the cat can be put back into the proverbial bag here - it seems impossible that Gabriel Lorca will still be the captain of the USS Discovery going forward.

This revelation raises just as many questions as it answers, like what happened to the main universe’s Lorca, how Mirror Lorca managed to jump universes, and if he brought anyone else along with him. It would certainly make sense if Commander Ellen Landry - Lorca’s closest confidante, who was killed in the series’ fourth episode - was another intruder from that universe, and would make Lorca’s seeming ambivalence about her death feel slightly less strange.

Next week’s episode appears to be at least a partial flashback to the events that led Lorca to pursue his revolt against Georgiou and jump universes, so we should get some more context for this shocker fairly soon. Even so, this is a massive moment for Discovery, essentially blowing up the show’s most potent dynamic between Lorca and Burnham. We’ll soon see if this was a genius twist or an unfortunate misstep.

More: Star Trek Discovery is Still Missing the Spirit of Star Trek

Star Trek: Discovery continues next Sunday, January 28th with “What’s Past Is Prologue” on CBS All Access.