The film was released on November 3, 2017. A sequel, Thor: Love and Thunder, is in development and scheduled for release in 2021.
Two years after the battle of Sokovia, Thor is imprisoned by the fire demon Surtur, who reveals that Thor's father Odin is no longer on Asgard. He explains that the realm will soon be destroyed during the prophesied Ragnarök, once Surtur unites his crown with the Eternal Flame that burns in Odin's vault. Thor frees himself, defeats Surtur and takes his crown, believing he has prevented Ragnarök.
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.
The Grandmaster orders 142 and Loki to find Thor and Hulk, but the pair come to blows and Loki forces her to relive the deaths of her fellow Valkyrior at the hands of Hela. Deciding to help Thor, she takes Loki captive. Unwilling to be left behind, Loki provides the group with the means to steal one of the Grandmaster's ships. They then liberate the other gladiators who, led by[dubious – discuss] two aliens named Korg and Miek, stage a revolution. Loki again attempts to betray his brother, but Thor anticipates this and leaves him behind, where Korg, Miek, and the gladiators soon find him. Thor, Banner, and 142 escape through a wormhole to Asgard, where Hela's forces are attacking Heimdall and the remaining Asgardians in pursuit of the sword that controls the Bifröst. Banner chooses to become Hulk again, defeating Fenris, while Thor and 142 battle Hela and her warriors. Loki and the gladiators arrive to rescue the citizens, and a repentant Skurge sacrifices himself to enable their escape. Thor, facing Hela, loses his right eye and then has a vision of Odin that helps him realize only Ragnarök can stop her. He sends Loki to retrieve Surtur's crown and place it in the Eternal Flame. Surtur is reborn and destroys Asgard, seemingly killing Hela.
Aboard the Grandmaster's spaceship, Thor, now king, decides to take his people to Earth. In a mid-credits scene, they are intercepted by a large spacecraft. In a post-credits scene, the Grandmaster is confronted by his former subjects.
- Chris Hemsworth as Thor
- Tom Hiddleston as Loki
- Cate Blanchett as Hela
- Idris Elba as Heimdall
- Jeff Goldblum as Grandmaster
- Tessa Thompson as Valkyrie
- Karl Urban as Skurge
- Mark Ruffalo as Bruce Banner / Hulk
- Anthony Hopkins as Odin