Let's figure out where that missing stone is.
Thanks to a library of Marvel Cinematic Universe movies, the locations of the Infinity Stones at the heart of the conflict in Avengers: Infinity War are well-known. With six stones needed to complete the Infinity Gauntlet, which the film's latest trailer says will allow Thanos (Josh Brolin) to wipe out half of the universe, five of them are already in play.
What about the sixth, though? The Soul Stone has yet to be discovered in the MCU, but there are several clues to try to figure out exactly where it is. Take a look at the video above to find out everything GameSpot knows about this particular Infinity Stone.
While fans haven't seen this stone appear in a movie, it has been mentioned. In the comic book "Avengers: Infinity War Prelude #2," Wong (Benedict Wong) tells Doctor Strange (Benedict Cumberbatch) that the Soul Stone could potentially be the most important and dangerous of the six glowing rocks.
GameSpot previously theorized that the stone was responsible for the heart-shaped herb in Wakanda, which give the Black Panther his powers. However, Infinity War co-director Anthony Russo said that's not what brings Thanos to the country. Instead, he's actually hunting Vision, who is powered by the Mind Stone. So while the Soul Stone could be there, it seems unlikely.
Other theories about the stone's location range from Heimdall (Idris Elba) having possession to Adam Warlock--teased during a post-credits scene in Guardians of the Galaxy Vol. 2--somehow being involved. Then again, it's also possible that Tony Stark (Robert Downey Jr.), himself, is the holder of the Soul Stone.
When it comes to this final piece of the Infinity War puzzle, there are a number of outcomes. Of course, the only way you'll find out the answer for sure is when Avengers: Infinity War hits theaters on April 27.