Thor: Ragnarok - 7 Predictions For The Huge Surprise

3. The Secret Of The Soul Stone

For a while now, it's looked like Heimdall might be the key to discovering where the Soul Stone is in the MCU (particularly as his eyes seem to glow the same colour as the Stone).

Since then, a more compelling theory has surfaced suggesting that his master, Odin, might be the one who wields the Stone, with it being the source of his OdinForce, just as the other Stones have been shown to be behind other powers in previous movies.

By the look of the marketing, Hela starts the movie (in flashback) with significantly more powers than when she first returns, and they then return to her, suggesting something big changes for her. Shockingly, that could mean that she kills off Odin, destroys the OdinForce (and significantly depowers Thor in the process) and takes the Stone for herself to rise back to full power.