Contains spoilers for “Mission: Impossible — The Final Reckoning”

As “Mission: Impossible — The Final Reckoning” begins soon after the events of “Mission: Impossible — Dead Reckoning Part One,” the formidable artificial intelligence known as the Entity remains a significant threat to humanity. However, Ethan Hunt (Tom Cruise) has successfully retrieved the key from Gabriel (Esai Morales), granting him the potential to access the Entity’s source code, which is hidden within a submerged Russian submarine. Many might not have anticipated the significance of “Mission: Impossible III,” one of the franchise’s top films, to this intriguing twist in the storyline of the new movie.

In the third installment of the franchise, Ethan undertakes the mission to steal an object called the Rabbit’s Foot. The film never clarifies its nature, although Benji (Simon Pegg) alludes to it as something that could cause “end-of-the-world kinda stuff.” Since its introduction, the Rabbit’s Foot has persisted as one of the franchise’s most enigmatic elements, often dismissed by fans as an ambiguous MacGuffin. Whether it was a bomb, a bioweapon, or something else never seemed significant; its role was to propel the narrative of “MI:III” forward. However, “Final Reckoning” unveils its true importance, revealing that the Rabbit’s Foot originated as the source of the Entity.

The catastrophic threat encased within the Rabbit’s Foot was an early version of the immensely powerful artificial intelligence that Ethan and his team face now. Over the two decades between “Mission: Impossible III” and “Final Reckoning,” the Entity evolved, acquiring control over nuclear arsenals worldwide. When organizing your next “Mission: Impossible” movie marathon, consider placing the third film ahead of “Dead Reckoning.” This adjustment makes sense, as “Final Reckoning” acts as a thematic revisit of “MI:III,” with Ethan once again undertaking a mission to steal the source code, now from a submarine, to thwart the Entity’s nefarious plans.

It’s a common trope in pop culture for heroes to make their own villains. Batman causes Joker to fall into a vat of acid; Luke Skywalker’s actions cause Ben Solo to turn to the Dark Side; and Ethan Hunt’s theft of the Rabbit’s Foot inadvertently allows it to grow into a world-ending threat. Ethan was originally tasked with stealing the Rabbit’s Foot in “M:I:III” by Owen Davian (Phillip Seymour Hoffman). In the end, Davian dies and the Rabbit’s Foot winds up in possession of the Impossible Mission Force.

Ethan undoubtedly thought he was doing the right thing turning over a powerful weapon (that he had no idea was an AI) to the United States government in 2006. He didn’t know that Denlinger (Cary Elwes), the director of the country’s National Intelligence, would begin to unleash the AI, still in its infancy, against foreign threats. This included using it against the Sevastopol submarine in 2012, which is when it gained sentience and sunk the vessel so that its source code, the only thing that could defeat itself, would be housed safely at the bottom of the sea.

Retconning the Rabbit’s Foot to be an AI prototype that Ethan helped unleash adds a personal angle to “Final Reckoning’s” story. But while he inadvertently brought armageddon to the world’s doorstep, no AI is a match for the living embodiment of destiny that is Ethan Hunt.

It’s unlikely that the team behind “Mission: Impossible III” intended the Rabbit’s Foot to be an AI. After all, the vial it’s in is marked “Biohazard,” which doesn’t really make sense unless it was labeled as such to throw people off the scent of what it truly was. (Of course, it does become a general threat to all life as we know it, which in turn makes it a hazard to all biological life, but we digress.) That said, there is a line in “M:I:III” that helps connect the Rabbit’s foot to “Final Reckoning” in a fairly clever manner.

When asked what the Rabbit’s Foot is, Benji describes it as an “unstoppable force of destructive power that would just lay waste to everything … So whenever I see, like, a rogue organization willing to spend this amount of money on a mystery tech, I always assume … it’s the Anti-God.” The term “Anti-God” becomes particularly prudent, as the Entity has formed its own doomsday cult in “Mission: Impossible — The Final Reckoning.” These are individuals who want to aid the Entity in bringing about the end of the world, giving the threat an almost religious connotation as we see them try to prevent Ethan and his allies from halting the evil AI’s mission.

The Entity has literally become an Anti-God that wants to end all life. Fortunately, “Mission: Impossible III” was so vague in its description of the Rabbit’s Foot, it was brought back virtually seamlessly all these years later.

“Mission: Impossible — The Final Reckoning” is in theaters now.