The trailer reveals how and why Tom Hiddleston’s Loki returns after his defeat in The Avengers. Thor, played by Chris Hemsworth, visits him in prison and pulls him out because he is the only one who knows how to deal with the threat that has emerged.
The video also shows plenty of action in London and in Asgard as the villains wreak havoc and destruction throughout the different worlds. Natalie Portman’s Jane Foster ominously says that the fabric of reality could unravel, seemingly if the threat is not stopped.