Amazon’s Fallout TV series offers a shocking (and undoubtedly controversial) explanation for one of the game’s biggest mysteries.

For years, Fallout fans have wondered who started the nuclear war that eventually led to the end of the world as we know it. Well, Amazon’s Fallout series offers an answer to that question, and some fans may not be happy with what it has to say.

In the third act of the TV series, it is revealed that the nuclear war wasn’t started by one of the world’s warring countries but rather by Vault-Tec itself. Via a series of flashbacks, we learn that Vault-Tec detonated its own nukes, sparking the war between the U.S. and China that ravaged the planet’s surface. The main reason for such an evil act is simple: greed. After all, if there’s no war, Vault-Tec’s most valuable product, a vault meant to protect citizens from nukes and the fallout thereafter, would go to waste.

Of course, profits are just one piece of the puzzle. According to the show, Vault-Tec also conspired with other American companies to dictate who was allowed to enter which vaults. They didn’t just sell vault space to the wealthy but also recruited scientists and others loyal to Vault-Tec, cryogenically freezing many of them to be thawed when it was time to reclaim the surface. By doing so, Vault-Tec could ensure the company had a greater say in who lived, who died, and, most importantly, who got to rule over whatever world was left.

So how is that different from what the Fallout games have to say about the origins of the event known as the Great War? Well, that’s a very good (and surprisingly complicated) question.

Fallout creator Tim Cain previously revealed last year that China was the first country to launch a nuclear weapon in the Great War that ended the world. More specifically, he explained that China learned that the United States was working on a deadly weaponized virus and launched nukes at the U.S. to prevent that virus’ subsequent development and eventual deployment.

As you might expect, that reveal from Cain was quite the bombshell for fans. After all, the mystery of who launched the first nuke had long been one of the Fallout series’ most debated (and essential) pieces of lore. It was shocking to hear Cain share such a clear-cut answer to that question during a random podcast appearance. Even Cain seemed to be taken aback by his statements, as he quickly tried to backtrack from the China shot first argument by suggesting that the launch may have originated from some “rogue nation.”

The ambiguity that surrounded the answer to the big question is at the heart of this entire discussion. For quite some time, the subject of who launched the first nuclear weapon has felt less important than the social and political issues that eventually escalated into global nuclear warfare. While fans loved to debate the specifics of the matter, there seemed to be a general agreement that who launched the first bomb was an intentionally unanswerable question. That’s what makes the show’s decision to openly address that topic so surprising.

Yet, the show’s Vault-Tec answer isn’t quite as far-fetched as it may initially appear to be. Fans have long theorized that Vault-Tec was either directly responsible for the war or was at least one of the factions that added considerable fuel to that fire. While the games have never directly stated that Vault-Tec nuked their home country for business reasons, that theory has certainly been tossed around in the past. In fact, the script for a canceled Fallout film that Interplay wanted to make in the late ‘90s also featured the idea that Vault-Tec launched the first nuclear weapon.

What makes this whole thing particularly tricky, though, is Bethesda’s insistence that they are treating Amazon’s Fallout series as canon. That would not only suggests that Fallout 5 will eventually honor this new origin story, but that previous Fallout games (or at least the Bethesda entries in that series) also now exist within that context. That’s of course assuming that “Vault-Tec shot first” will not be altered in any significant ways by future seasons of Amazon’s Fallout series.

Granted, the recent history of massive multimedia franchises has made it clear that war may never change but lore certainly does. We’ll have to wait and see if future Fallout games honor this shocking revelation or if this whole thing is just a case of the right hand being indifferent to the specifics of the left hand’s adaption. As for whether or not this is a satisfying explanation for one of Fallout‘s greatest mysteries…well, that’s something that fans will ultimately need to decide for themselves.