If you're a character in the Marvel Cinematic Universe people are going to wonder why you aren't appearing. Since continuity means that characters aren't as easily written out as they used to be in movies the absence of an existing character can be just as telling as the addition of a new one. In this case it's the absence of an existing character that has people talking.
The character in question is Lady Sif played by Jamie Alexander. Sif played a pretty big role in both of the Thor movies so far and was even being set up as a love interest in Thor: The Dark World. However, we haven't seen a single image from her in the new movie so what happened to Lady Sif? Screen Rant asked Marvel mega producer Kevin Feige about what happened to Sif and he his answer was a bit cryptic.
You're the second person to ask me that question today and I will quote Maz Kanada from Star Wars: The Force Awakens, "that is a good question for another time." Is that the quote? It's pretty close to that.
So what does all of this mean? Well it certainly looks like Asgard is going to get the crap kicked out of it by Hela so there is a good chance she could die. Alexander has a good gig going on her television show and they could be writing her out. Sif is a great character though with a ton of potential and the Thor series has already lost one female character in Jane (Natalie Portman). It would be a shame if they just killed off off screen.
Summary: Imprisoned, the mighty Thor finds himself in a lethal gladiatorial contest against the Hulk, his former ally. Thor must fight for survival and race against time to prevent the all-powerful Hela from destroying his home and the Asgardian civilization.
Thor: Ragnarok, directed by Taika Waititi, stars Chris Hemsworth, Tom Hiddleston, Cate Blanchett, Jeff Goldblum, Idris Elba, and Mark Ruffalo. It will be released on October 24th in the UK and November 3rd in the US.