The plot of the movie will see Thanos collecting the Infinity Stones, but the location of the Soul Stone in particular has not been alluded to in any MCU movie so far.
Speculation was rife that it would be seen in Black Panther, and even though that didn’t happen, theories continue to come thick and fast that it is in Wakanda after all.
This new theory, however, resurfaces what many die-hard Marvel fans have long suspected: the key is Heimdall, the character played by Idris Elba.
Reddit user twistediniquity said: “I just can’t get behind this theory that the Soul Stone is in Wakanda. To me, it doesn’t make sense. After watching the trailer, what does make sense is: The Avengers know that Thanos wants the Infinity gems.
“They know they have two, so obviously you protect them in the most technologically advanced place on the planet. That’s why there is a fight in Wakanda. The soul stone has nothing to do with vibranium. The powers and colour schemes do not match at all, and these movies love to be aesthetically pleasing.
“What does match? Heimdall.”
They added: “In Thor, it was explained: Heimdall can see anyone in the universe. Then, in Age of Ultron: During Thor’s Scarlet Witch nightmare. Heimdall is blinded, making me think that Thor’s nightmare was his worst fears. Of a dead Asgard, and of a powerless Heimdall because he understands what Heimdall has.
“THOR RAGNAROK: Heimdall pulled Thor’s soul from his body to speak with him. Not to mention Heimdall’s eyes. He is the only character with orange eyes. And they were grey when he was blinded in Thor’s nightmare.
“If Heimdall isn’t holding the soul stone, I will be very disappointed.”
Without any other real tangible hints to work with, it’s certainly a feasible theory – does Heimdall hold the key to the Soul Stone?
We don’t have long to wait before we find out: Avengers: Infinity War is out on April 26.