WARNING: This article contains SPOILERS for Black Panther
Black Panther may have hidden the final Infinity Stone in plain sight, setting the stage for Infinity War without fans even noticing. You would think that such a task would be impossible to achieve, as fans of Marvel's Cinematic Universe search for the Soul Stone in every possible place (along with Thanos, the Mad Titan). The final piece of the puzzle for Marvel's Phase 3 showdown was expected by many to be revealed in Black Panther. But the record-breaking blockbuster told its own story, instead of worrying about setting up Infinity War... right?
The story of T'Challa and Wakanda's introduction to the world still made time for some MCU nods, most notably showing Bucky's return after his Civil War antics. But hopes that the movie's villain would be seeking the Soul Stone, or that its location would be revealed in an end-credits stinger went unfulfilled. In fact, even the director Ryan Coogler offered an explanation for why disappointed fans didn't get to see an Infinity Stone worked into Black Panther's fiction. But just because the characters don't KNOW it's an Infinity Stone, that doesn't mean fans can't spot the evidence.
Make no mistake: Marvel's Black Panther movie can be enjoyed on its own, with no connection to the larger MCU at all. But with so many Black Panther characters returning for Infinity War and the nation of Wakanda playing a pivotal role, taking their history, technology, and spirituality at face value seems foolish. Especially when the final, missing Soul Stone would explain an awful lot about Wakanda and its Black Panther mythology.
You can bet Thanos is doing some detective work, so MCU fans should, as well.
This Page: The Infinity Gauntlet's Missing Soul Stone Explained
The Soul Stone: The Missing Piece of Infinity War's Puzzle
As the first of the Infinity Stones to enter Marvel mythology (originally all referred to as other "Soul Gems"), the rules and power of the Soul Stone changed in the early years. But eventually the mythology solidified, making the Soul Stone one of the most unsettling, and supernaturally powerful of the group. Why? Because the Soul Stone isn't merely a weapon to be used by Thanos, or any other cosmic conqueror... it has a mind of its own. Literally.
The Infinity Stones of Marvel's movie universe have mainly been portrayed as items of immense power, not sentient forces working to feed their varied appetites. That's how the comics started, too, until the Soul Stone's first owner (Adam Warlock) discovered a being behind the object's power. Those MCU fans with flawless memory will recognize the hints of such sentience in the movies: Loki's Scepter (the Mind Stone in disguise) working to sow resentment among the Avengers. And later, when it changed color and spawned an artificial intelligence of sorts, named Ultron. Then there was the Power Stone, apparently choosing Jane Foster as its host in the form of Thor: The Dark World's Aether.
As the name might imply, the Soul Stone craves souls, as Adam Warlock soon learned - a dark hunger that shaped his future from that point forward. But what makes the Soul Stone so dangerous, and what provides a clue as to its place in the MCU, is what it's willing to give in exchange for a soul. In short: Paradise.
The other powers granted to the wielder of the Soul Stone are direct enough: the gift of superhuman protection and power, and the ability to evolve or de-evolve life forms (and spare one's soul by feeding it the souls of others). But it's that promise of the Soul Stone beyond the grave that's most important to our theory. Because it doesn't take much to see that same power as the source of Black Panther's greatness - and that of his native Wakanda.
The hero and his people may have the Soul Stone to thank. The Soul Stone delivered to Earth in the form of vibranium meteorite, that is.