New official plot descriptions for Thor: Ragnarok and Guardians of the Galaxy Vol. 2 have been revealed as part of a 2017 Walt Disney Studios press kit. Although mainly just confirming and organizing previously-known plot points, the plot details for the third Thor film do confirm that the titular character will be without his hammer for a majority of the movie. That's a unique coincidence, given in current Marvel Comics' continuity Thor lost the rights to his hammer by becoming "unworthy," with it finding a new partner in Jane Foster - who becomes the new Thor.
"In Marvel Studios' Thor: Ragnarok, Thor is imprisoned on the other side of his universe without his mighty hammer and finds himself in a race against time to get back to Asgard to stop Ragnarok - the destruction of his homeworld and the end of Asgardian civilization - at the hands of an all-powerful new threat, the ruthless Hela. But first he must survive a deadly gladiatorial contest that pits him against his former ally and fellow Avenger - the Incredible Hulk!"
The Guardians of the Galaxy Vol. 2 synopsis continues to stress the mystery of Star-Lord's father, while not mentioning any specific villains at all.
"Set to the all-new sonic backdrop of Awesome Mixtape #2, Marvel's Guardians of the Galaxy Vol. 2 continues the team's adventures as they traverse the outer reaches of the cosmos. The Guardians must fight to keep their newfound family together as they unrvavel the mystery of Peter Quill's true parentage. Old foes become new allies and fan-favorite characters from the classic comics will come to our heroes' aid as the Marvel Cinematic Universe continues to expand."
Guardians of the Galaxy Vol. 2 is due out May 5, while Thor: Ragnarok is scheduled for November 3.