Black Panther is due to release in one week, and while it's crazy to think that there could be anything else arriving in theaters BEYOND this extremely hyped film that has already inspired heartwarming praise, Avengers: Infinity War will be here before we know it. The blockbuster to end all blockbusters will finally deliver on the long-gestating storyline of the Infinity Stones, but obsessive fans know that there is one stone still left to go: the Soul Stone. With only one movie left before Infinity War, it feels like a safe bet that the stone will finally be introduced in Black Panther.
This movie might not seem like the most logical place to introduce a cosmic object of unimaginable power. Thor: Ragnarok, which actually takes place in space, makes more sense on a purely surface level, but Black Panther is actually a pretty great (and feasible) choice to show off the Soul Stone thanks to Wakanda's deep spirituality.
Oh, and the city of ghosts. That's important, too.
For a quick refresher, the Soul Stone is the only Infinity Stone -- the cosmic MacGuffins that appear in several MCU movies -- that has yet to be revealed. Thanos is trying to gather these objects of power together, which would allow him to control all of existence. While the movies are liable to tweak the stone's powers, in the comics the Soul Stone allows the user to control, steal, manipulate, and alter the soul of a living or dead person.
Wakanda happens to have a place where the living and the dead can communicate freely. It's called Necropolis, the final resting place of all Black Panthers. The spirits tend to hang around, providing wisdom and advice to the current Panther. In the comics, T'Challa is, at one point, named the King of the Dead and he is given full access to the abilities and knowledge of every previous Black Panther. He also uses Necropolis as a secret base of sorts, which eventually becomes a prison to the one and only Thanos.
Knowing this, it's not so farfetched to think that in the MCU, the Soul Stone resides in Wakanda, where its supernatural abilities allow Black Panther to communicate with the dead. Perhaps it's an item of worship of some kind in Wakanda, housed in some kind of secret temple. There's actually quite a bit of evidence to support that the Soul Stone is in Black Panther.
We know from the trailers that at one point in the movie, T'Challa has some kind of dream/vision. He walks toward a tree full of bright-eyed panthers, the sky above shining a bright purple. It's possible that this is how T'Challa communicates with past Panthers (or Panther gods), and the Soul Stone could be his method of doing this. Being able to launch the user into a spirit quest certainly sounds right up the alley of something called the Soul Stone.
Seeing as how I haven't seen the movie yet, I'm probably assuming a lot of Wakanda's religion and culture, yet there is some tease that Wakandans believe in life after death. In Captain America: Civil War, after T'Challa's father dies, he tells Black Widow that his people don't believe that death is the end. It's "more of a stepping off point." It's a nice bit of world-building, but it could also be a sly tease of things to come.
Another strong piece of evidence is the fact that Wakanda serves as a major set piece in Avengers: Infinity War. The trailers show off a massive battle between the armies or Wakanda and Thanos, with no explicit reason given as to why the battle is happening. It could be that Thanos is just trying to take the most powerful player out of the game, but considering that Thanos' whole objective in this movie is to find the Infinity Stones, he could also be launching an assault to claim the Soul Stone from Wakanda. It would certainly justify why so many of the Avengers are present as they make a grandstand to stop the final stone from reaching Thanos' clutches.
While the evidence is in favor of the Soul Stone being in Black Panther, there's also a chance it won't be introduced until Infinity War. Marvel doesn't have the best track record when it comes to inserting the stones into other movies gracefully. Sometimes it works, but more often than not, it's about as distracting as a magic hot tub. Maybe Marvel didn't want to impose anything on Ryan Coogler, arguably the most talented auteur they've ever recruited, and just wanted him to make the movie he wanted.
Regardless, the evidence is much more in favor of the Soul Stone being in Black Panther than it isn't. Not only would Wakanda have a solid connection to the stone through Necropolis, but it would also save Infinity War the screentime it would take to explain the Soul Stone -- screentime it really can't afford.