Following Thanos’s activation of the Meanwhile, Carol Danvers rescues Nebula and Tony Stark, who are stranded in space following their defeat by Thanos. She returns them on Earth. The team tries to retrieve the Infinity Stones from Thanos to reverse his actions, but find he has destroyed them to prevent further use. Thanos is decapitated by Thor.
Five years later, Banner has merged with the Hulk and Thor has become the fat and drunken ruler of Asgard’s refugees in Tønsberg, Norway. Scott Lang escapes from the quantum realm[N 2] and finds Romanoff and Rogers at the Avengers’ compound, theorizing that the quantum realm can allow time travel. The three propose to Stark — now raising a daughter, Morgan, with Pepper — that they travel back in time to retrieve the Infinity Stones before Thanos can collect them. Stark rejects, concerned what altering history will mean for Morgan, but relents after reflecting upon the loss of Peter Parker and designs a working time machine.
The reunited Avengers split into groups for their mission. Banner, Rogers, Lang, and Stark travel to the Battle of New York[N 3] to retrieve the Time, Mind, and Space Stones. Banner visits the Sanctum Sanctorum and convinces the Ancient One to give him the Time Stone, Rogers steals the Mind Stone from undercover Hydra agents and stumbles across and fights his past self, and Lang and Stark’s attempt to steal the Space Stone fails when the distraction they cause enables Loki to escape with it. While Lang and Banner return to the present, Rogers and Stark travel further back to the U.S. Army’s Fort Leigh in 1970,[N 4] to steal both an earlier version of the Space Stone and vials of Hank Pym’s size-altering Pym Particles to return home afterwards. Rogers sees Peggy Carter, Stark meets his father Howard, and the pair succeed.
In Asgard, Rocket and Thor retrieve the Reality Stone from Jane Foster.[N 5] Thor has a chance encounter with his mother Frigga, whose counsel restores his conviction, and obtains a past version of his hammer, Mjolnir.[N 6] Barton and Romanoff arrive on Vormir for the Soul Stone. They learn from its keeper, Red Skull, that it can only be retrieved by sacrificing someone they love. They fight over who should be the sacrifice, but ultimately Romanoff sacrifices herself.
On Morag, Nebula and Rhodes steal the Power Stone before Peter Quill.[N 7] Rhodes returns it to the present, but Nebula is left stranded behind as her cybernetic implants interface with those of her past self, which Thanos exploits and learns of his future success and the Avengers’ attempt to thwart him. He sends the past incarnation of Nebula to the present in Nebula’s place.
Banner uses the Infinity Stones to resurrect everyone killed by Thanos, while Nebula’s past self uses the time machine to transport Thanos and his army from the past to the Avengers’ facility. They reduce it to rubble, and Barton recovers the Infinity Stones in the chaos. The past Nebula is killed by her present-day self, while Rogers, Thor, and Stark confront Thanos, now planning to use the Infinity Stones to destroy the universe and create a new one with no memory of the original. Rogers proves able to lift Thor’s hammer, while Doctor Strange and Wong arrive and teleport all of the revived Avengers and others, including the armies of Wakanda and Asgard, to battle Thanos. Stark eventually retrieves and activates the Infinity Stones, which disintegrates Thanos and his army, though Stark himself is fatally wounded.
Following a funeral for Stark, Thor appoints Valkyrie queen of Asgard and joins the Guardians of the Galaxy. Rogers returns the Infinity Stones and Thor’s hammer to their original timelines, then lives out his life in the past with Carter instead of returning to the present. As an elderly man, he arrives to pass on his shield to Sam Wilson.