Thor: Ragnarok is a 2017 American superhero film based on the Marvel Comics character Thor, produced by Marvel Studios and distributed by Walt Disney Studios Motion Pictures. It is the sequel to 2011’s Thor and 2013’s Thor: The Dark World, and is the seventeenth film in the Marvel Cinematic Universe (MCU).
Thor returns to Asgard to find Heimdall gone and his brother Loki posing as Odin. After exposing Loki, Thor forces him to help find their father, and with directions from Stephen Strange on Earth, they locate Odin in Norway. Odin explains that he is dying and Ragnarök is imminent despite Thor’s efforts to prevent it. He then reveals his passing will allow his firstborn child, Hela, to escape from a prison she was sealed in long ago. Hela was the leader of Asgard’s armies, conquering the Nine Realms with Odin, but Odin imprisoned her and wrote her out of history after he feared that she had become too ambitious and powerful. Odin dies as Thor and Loki watch on, and Hela appears, destroying Thor’s hammer Mjolnir. She pursues the two as they attempt to flee through the Bifröst Bridge, forcing them out into space. Arriving in Asgard, she defeats its army and kills the Warriors Three. She then resurrects the ancient dead who once fought with her, including her giant wolf Fenris, and appoints the Asgardian Skurge as her executioner. Hela plans to use the Bifröst to expand Asgard’s empire, but Heimdall sneaks in, takes the sword that controls the Bridge and begins hiding other Asgardians.
Thor crash-lands on Sakaar, a garbage planet surrounded by wormholes. A slave trader designated Scrapper 142 subdues him with an obedience disk and sells him as a gladiator to Sakaar’s ruler, the Grandmaster, with whom Loki has already ingratiated himself. Thor recognizes 142 as one of the Valkyrior, a legendary force of female warriors who were killed fighting Hela long ago. Thor is forced to compete in the Grandmaster’s Contest of Champions, facing his old friend Hulk. Summoning lightning, Thor gets the upper hand, but the Grandmaster sabotages the fight to ensure Hulk’s victory. Still enslaved after the fight, Thor attempts to convince Hulk and 142 to help him save Asgard, but neither is willing. He soon manages to escape the palace and finds the Quinjet that brought Hulk to Sakaar. Hulk follows Thor to the Quinjet, where a recording of Natasha Romanoff makes him transform back into Bruce Banner for the first time since Sokovia.