After the destruction of Asgard, the refugee vessel Statesman drifts through space carrying the last survivors of Thor’s people. Their escape is cut short when Thanos and his flagship, the Sanctuary II, intercept the ship. The Mad Titan has already begun gathering the Infinity Stones and now seeks the Tesseract, hidden among the Asgardians. With Thor beaten and Heimdall gravely wounded, Thanos demands that Loki surrender it. When Loki hesitates, Thanos uses the Power Stone to torture Thor until Loki finally reveals the cube.
Even after handing it over, Loki attempts one final act of defiance. Hulk bursts forward and attacks Thanos, but the Titan easily overpowers him in brutal combat. Thor is restrained, and the remaining Asgardians are helpless. Heimdall uses the last of his life force to summon the Bifrost and send Hulk to Earth. Furious, Thanos kills Heimdall, crushes the Tesseract to claim the Space Stone, and then murders Loki after seeing through his attempted deception. With two stones now in the Gauntlet, Thanos destroys the Statesman and departs, leaving Thor adrift in the wreckage.
Hulk crashes through the roof of the New York Sanctum and transforms back into Bruce Banner. He warns Doctor Strange and Wong that Thanos is coming for the stones on Earth. Strange and Banner find Tony Stark and explain that the Time Stone, guarded by Strange, and the Mind Stone, housed in Vision’s forehead, are Thanos’ next targets. Banner urges Tony to contact Steve Rogers despite the rift that split the Avengers. Before Tony can decide, a giant alien ship appears over Manhattan.
Ebony Maw and Cull Obsidian descend into the streets of New York and attack in search of the Time Stone. Strange, Stark, Wong, and Banner engage them while chaos spreads across the city. Peter Parker sees the disturbance from a school bus and rushes to help. During the battle, Tony activates the Iron Spider suit for Peter. Maw eventually captures Strange and lifts him aboard his Q-Ship, but Iron Man and Spider-Man pursue the vessel into space. Wong returns to protect the Sanctum, while Banner, still unable to transform into Hulk, uses Stark’s phone to call Steve Rogers.
Far from Earth, Thor is discovered floating in space by the Guardians of the Galaxy. Once revived aboard their ship, he explains that Thanos slaughtered half the Asgardians and already took the Power Stone from Xandar. Gamora, who was raised by Thanos, warns that if he gains all six stones he can wipe out half of all life with a snap of his fingers. Realizing Thanos will likely seek the Reality Stone on Knowhere, the Guardians split up. Thor travels with Rocket and Groot to Nidavellir to forge a weapon powerful enough to kill Thanos, while the others race to Knowhere.
Meanwhile in Scotland, Vision and Wanda Maximoff attempt to live quietly together in secret. Their brief peace ends when Proxima Midnight and Corvus Glaive ambush them for the Mind Stone. Vision is badly wounded and weakened, while Wanda struggles to defend them both. Before they are overwhelmed, Steve Rogers, Natasha Romanoff, and Sam Wilson arrive and drive the attackers back. They bring Vision and Wanda to the Avengers Compound, where old allies reunite under the shadow of Thanos’ coming invasion.
At Knowhere, Star-Lord, Gamora, Drax, and Mantis find devastation everywhere. They believe they have surprised Thanos, and Gamora even appears to kill him. But the scene is only an illusion created by the Reality Stone. Thanos has already taken the stone and anticipated Gamora’s arrival. He captures her, knowing she alone knows where the hidden Soul Stone lies. Quill attempts to honor Gamora’s demand that he kill her rather than let Thanos use her, but the Titan turns his gunfire into harmless bubbles and vanishes with her.
On the Sanctuary II, Thanos pressures Gamora to reveal the Soul Stone’s location. She refuses until he begins torturing Nebula, slowly tearing her cybernetic body apart. Unable to endure her sister’s suffering, Gamora reveals that the Soul Stone can be found on Vormir. Though ruthless, Thanos genuinely seems pained by what he is forcing Gamora to do, hinting at the twisted affection he feels for his adopted daughters.
Thor, Rocket, and Groot arrive at Nidavellir and meet Eitri, the last surviving dwarf king. Eitri reveals that Thanos forced him to forge the Infinity Gauntlet, then slaughtered the dwarves and crippled him so he could never craft another weapon. Thor refuses to surrender to despair and convinces Eitri to help him forge Stormbreaker, a weapon capable of killing Thanos and summoning the Bifrost. To restart the forge, Thor endures the full force of a neutron star, nearly dying in the process. Groot sacrifices his arm as the handle, completing the axe and reviving Thor.
Aboard Maw’s ship, Iron Man and Spider-Man rescue Doctor Strange by blowing a hole in the hull, sending Ebony Maw into space. Strange wishes to return to Earth, but Tony insists they continue to Titan and confront Thanos there. When they arrive, they are ambushed by Star-Lord, Drax, and Mantis, who mistake them for enemies. Once the misunderstanding is cleared, the heroes unite. Strange then uses the Time Stone to look through over fourteen million possible futures, finding only one path to victory.
Thanos and Gamora travel to Vormir, where they are greeted by Red Skull, now cursed to guide seekers of the Soul Stone. He tells Thanos that the stone requires a sacrifice: one must lose what one loves most. Gamora laughs, believing Thanos incapable of love. But when she sees him weeping, she realizes the terrible truth. Thanos throws Gamora from the cliff, sacrificing the daughter he truly loved in his own warped way, and awakens with the Soul Stone in hand.
On Earth, the Avengers decide the only way to stop Thanos is to destroy the Mind Stone before he can claim it. Steve Rogers brings the team to Wakanda, where T’Challa offers sanctuary and Shuri begins trying to remove the stone from Vision without killing him. As she works, Thanos’ armies descend upon Wakanda in massive drop ships. T’Challa, Okoye, the Dora Milaje, M’Baku and the Jabari, Bucky Barnes, War Machine, Falcon, Black Widow, Banner in the Hulkbuster armor, and Rogers prepare for war.
The Outriders hurl themselves against Wakanda’s energy shield in overwhelming numbers. To prevent them from circling around and reaching Vision, T’Challa opens part of the barrier, forcing the creatures into a direct assault. A brutal battle erupts across the plains. Banner struggles without Hulk, but fights on in the Hulkbuster suit. The defenders hold the line as long as they can while Shuri races to finish her work.
On Titan, Thanos arrives and is met by the combined forces of Iron Man, Doctor Strange, Spider-Man, Star-Lord, Drax, Mantis, and Nebula. Their coordinated plan nearly succeeds. Mantis subdues Thanos’ mind while the others restrain him and try to pull the Gauntlet free. But when Nebula reveals that Gamora is dead, Quill loses control and attacks Thanos in grief and rage. The distraction breaks Mantis’ hold, allowing Thanos to recover and overpower them all.
The battle turns savage. Thanos uses the stones to counter every attack. Tony Stark fights with everything he has and even draws blood, but Thanos stabs him and prepares to kill him. To save Tony’s life, Strange surrenders the Time Stone, despite previously vowing never to do so. Thanos accepts and departs for Earth, leaving Stark confused as to why Strange would sacrifice the stone so easily.
In Wakanda, the Black Order renews its assault. Corvus Glaive infiltrates Shuri’s lab, halting the extraction process, while Cull Obsidian and Proxima Midnight attack the battlefield. Banner kills Cull, Vision helps destroy Glaive, and Wanda kills Proxima after joining the fight. Then Thor arrives with Rocket and Groot, unleashing Stormbreaker in a thunderous counterattack that turns the tide and inspires the exhausted defenders.
Victory seems near until Thanos suddenly appears in Wakanda through a portal. He sweeps aside everyone in his path, including T’Challa, Groot, and the remaining Avengers. Steve Rogers briefly resists him hand-to-hand, earning a moment of surprise from the Titan. Knowing there is no other choice, Vision asks Wanda to destroy the Mind Stone even though it will kill him. Heartbroken, she unleashes her power and shatters the stone, destroying Vision with it.
Thanos calmly uses the Time Stone to reverse the moment, restoring Vision and the Mind Stone. He tears the stone from Vision’s head, killing him permanently. With all six stones united in the Gauntlet, Thanos is finally complete. Thor hurls Stormbreaker into his chest, grievously wounding him. But Thor aims for revenge rather than certainty, and Thanos tells him he should have gone for the head.
Thanos snaps his fingers. A surge of cosmic energy ripples across the universe. He briefly enters a mysterious realm where a young Gamora asks what his victory cost. He answers softly: everything.
Returning to reality, Thanos escapes as heroes begin turning to dust. In Wakanda, Bucky Barnes vanishes first, followed by T’Challa, Groot, Wanda, and Sam Wilson. On Titan, Quill, Drax, Mantis, Strange, and finally Peter Parker disintegrate, leaving Tony Stark devastated. The survivors can do nothing but stare at the catastrophe they failed to stop.
Thanos retires alone to a distant peaceful world and watches the sunrise, satisfied that his mission is complete. In a post-credits scene, Nick Fury and Maria Hill witness the chaos spreading across Earth as people vanish and vehicles crash. Hill turns to dust, and Fury begins fading as well, but not before activating an old pager that sends a signal bearing the emblem of Captain Marvel.
