Mission: Impossible – Dead Reckoning's Big MacGuffin Raises As Many Questions As It Answers

This post contains spoilers for "Mission: Impossible – Dead Reckoning, Part One."

It's been five years but Tom Cruise is finally back in the saddle as Ethan Hunt on his biggest adventure yet in "Mission: Impossible – Dead Reckoning Part One." Yes, as the title implies, Cruise and director Christopher McQuarrie are ambitiously tackling a massive two-part story as the follow-up to 2018's "Fallout." It is, admittedly, a rather ambitious story that just so happens to be timely as well. The marketing did a pretty damn good job of hiding it, but Hunt and his IMF companions are fighting an artificially intelligent enemy this time around — albeit one with a dangerous human helper. And the whole movie hinges on a literal key that controls this powerful AI.

From the cold opening of the film, we come to learn that the big driving force of Ethan's mission this time around is a MacGuffin in the form of a cruciform key. This key is the only way of controlling the rogue AI at the center of the film known as The Entity. But there are a lot of moving parts in the movie — which is also a pretty long movie at that — and there is much to keep track of regarding this key, who has it, who wants it, and what it controls. So we're going to do our best to break down the key, how it works, and what we need answered in "Dead Reckoning Part Two." Let's dive in.

The cruciform key is the only thing capable of controlling The Entity. The key was aboard a Russian submarine called the Sevastopol from the beginning of the movie. That sub turned out to be a test gone wrong, as the AI proved to be more effective than anyone could have imagined. It went rogue (much like Ethan Hunt often does) and developed a mind of its own. The key is divided into two halves as a safety measure and the AI's source code can only be accessed when both authentic halves of the key are united.

While intelligence agencies around the world are aware of The Entity and the dangers it possesses for life as we know it, the bigger concern is that it has become a big, global power play. Whoever controls this powerful AI can control the future in many ways, becoming the unquestioned global superpower overnight. As such, every government around the world is trying to get its hands on the two halves of the cruciform key.

This includes the U.S. Government, which Ethan happens to work for. That quickly creates a conflict of interest, as he knows that the power this key controls is too much for any one man or governmental body to control. So, he decides to go rogue, find both halves of the key, and ensure that none of it falls into the wrong hands. Because this movie is a "Part One," the success or failure of the mission is left hanging in the air by the end of it, which means we're also left with some lingering questions about the key itself.

This is where things might get a little frustrating but there are many elements of the cruciform key in "Dead Reckoning Part One" that remain elusive by the time credits roll. And there is no post-credits scene to help tee up the ball for "Part Two." What we know for sure is that Ethan did manage to swipe the key from Gabriel (Esai Morales) during the movie's wild climactic train sequence. Gabriel is probably a good place to start when it comes to the question marks.

Gabriel is the human out there in the world looking to help The Entity, with The Entity seemingly helping him in turn. From erasing him in real time on security cameras to providing him with valuable information, this is the AI's right-hand man. But why is Gabrial in bed with The Entity? Why him? We know he has ties to Ethan's dark past, but is that really what this is all about? The particulars of his involvement were not fully clarified, and that's certainly a thread that needs pulling in the next installment.

There's also the Russian sub of it all. Why did the Russians have the key in the first place on that sub? Did the AI somehow generate from Russia in the first place? More importantly, why is the AI's source code now housed in that sub? The end of the film makes it incredibly clear that "Part Two" will be all about trying to get to the Sevastopol. For Ethan, it will be to shut this all down. For everyone else? They have various motivations. Some of which are unclear.

Grace (Haley Atwell) seemed to just be in it for money. The White Widow (Vanessa Kirby), on the surface, also wants money, but there seemed to be more going on with her than the movie explained. Again, more to explore in the sequel. And what of Gabriel? What will he do if he gets the key? It seems like he and The Entity are getting along just fine. Without getting into the nitty gritty of every character who touched the key in the film, the main thing is that not everyone's motivations were laid out clearly. It's easy to see why Kittridge (Henry Czerny) and his government would want it, which puts Ethan on the flip side of that coin. Everyone else? It's less clear.

Setting aside lingering questions, is the cruciform key an effective MacGuffin? Is this a good plot device? Or was there a better option? The problem with making AI the villain in a movie like this is that it's a non-tangible thing. It's hard to make a globe-trotting spy flick about computers. Would we want to watch Benji and Luther just spend two hours at a computer terminal with Ethan looking over their shoulders? Probably not.

In that way, having a key that required two halves to make it work did solve the problem of allowing AI to be the villain while also allowing this to still be a "Mission: Impossible" movie as we know it. At the same time, it's a plot device that created some holes that need filling in. So we can't say with certainty if this was a worthwhile thing to spend two movies chasing after until "Part Two" answers (or perhaps doesn't) some of the questions we're left with currently. Right now, a lot of it can be chalked up to a first-half hangover. McQuarrie and Cruise still have half a story left to tell.

"Mission: Impossible – Dead Reckoning Part One" is in theaters now.