The third installment of Thor: Thor Ragnorak is set to be release this November. For those of you who have seen the trailer, a new character not seen in previous movies made an introduction. This is Hela otherwise known as the death queen or mistress of the darkness.
Hela is said to be the daughter of Loki, the god of mischief, and the giantess Angrboda. The Asgardian Norns warned that Hela would one day be a danger to the realms. To combat this, Odin made her the ruler of hel and Niflheim. Her main purpose was to collect souls of the dead and she eventually aspired to collect the souls of Odin and Thor.
In the comics, Hela teamed up with Loki to bring out about Ragnarok,which according to Norse Mythology is the end of the universe.
This is essentially what it supposed to happen in the movie as we see characters such as Odin, Loki, Hela and the Valkyrie.
It is speculated that part of the movie might be set on earth as in the end credits for Dr. Strange, Thor was seen on earth searching for Loki and Odin. In the trailer for Thor it is seen that Thor is on earth and Hela destroys the Mjorlin. This could explain why Thor is seen in chains and banished from Asgard and sent to Sakaar. From there he is seen to be captured by Valkyrie and is set to fight Hulk. Although not seen in the trailer Thor needs to return to Asgard to stop Hela and save Asgard from Ragnorak.