Avengers: Endgame

The survivors are: Rogers, Stark, Thor, Banner, Romanoff, Barton, Rhodey, Nebula, Rocket, Carol Danvers, Okoye, Pepper Potts, M'Baku, Wong, Happy Hogan — and Scott Lang, stranded and unaccounted for.

Twenty-three days after the Snap, Danvers locates Thanos on a remote planet. He has already used the Stones a second time to destroy the Stones, so there is nothing to undo. Thor beheads him with Stormbreaker, on the spot, in about three seconds. It accomplishes nothing, and the guilt of not aiming for the head the first time is what breaks him for five years. The film jumps forward.

The world in 2023 is grief. Rogers runs support groups. Romanoff runs what's left of the Avengers alone. Stark has married Pepper Potts and has a daughter, Morgan, and refuses to help because helping means risking losing her. Thor has retreated into alcoholism and depression in New Asgard. Banner has merged his two selves into "Smart Hulk." Barton, having lost his entire family, has become a mass-murdering vigilante called Ronin.

"Smart Hulk" — yes, Banner is big and green, permanently. He looks like Hulk but wears glasses and cardigans, speaks in Banner's voice and vocabulary, and has Banner's personality entirely. He achieved it with eighteen months in a gamma lab deliberately fusing the two selves.

"Ronin" is not an organisation, it's an identity Clint invents. After the Snap kills Laura and all three of his children in front of him, he abandons the Hawkeye name and spends five years travelling the world murdering criminals who survived and he felt didn't deserve to — yakuza, cartels, mafias. Natasha finds him in Tokyo and brings him back.

The consequences catch up with him in Hawkeye (series), where Maya Lopez hunts him for killing her father.

New Asgard is in Tønsberg, Norway — the same coastal town Odin hid the Tesseract in centuries earlier. There is no Bifröst: Asgard the realm was destroyed in Ragnarok, and the bridge before that.

Thor: Love and Thunder later shows Asgardians travelling via a Bifröst opened by Stormbreaker — so travel is possible, but tied to Thor's axe rather than to a place.

Scott Lang escapes the Quantum Realm — five hours for him, five years for everyone else — and realises time works differently down there. Stark cracks the physics. They mount a time heist: teams travel to past moments to borrow the Stones before Thanos takes them.

None of this is conventional time travel. The Quantum Realm sits outside linear time, so you can enter at one point and exit at another. Stark solves the navigation problem overnight — an inverted Möbius strip — after seeing an old photo of himself and Peter Parker.

They build Quantum GPS suits and Pym Particle vials, and each person gets exactly two particles: one out, one back. That constraint drives the whole second act.

The film's stated rule is that you cannot change your own past. Altering the past creates a branched timeline and leaves your present untouched. Which is precisely why the Stones must be returned afterwards — to prevent branches forming.

Whether the people in the past notice varies case by case, and it is one of the most enjoyable things in the film:

• 2012 Rogers does not know. He thinks he's fighting a Loki illusion. Present-Rogers wins the fight by saying "Bucky is alive," which stuns him
• Howard Stark (1970) does not know. Tony introduces himself as "Howard Potts." Howard finds him oddly familiar and nothing more
• Frigga (2013) does know, instantly. She's a witch; she tells Thor she can see he's from the future and doesn't care
• The Ancient One (2012) knows, because Banner is holding the Time Stone and she can see the branch forming
• 2014 Thanos learns everything, which is the disaster

Key events: Rogers fights his 2012 self; Stark meets his father in 1970 and gets the conversation he never had; Thor speaks to Frigga on the day she dies and gets absolution; Banner obtains the Time Stone from the Ancient One by explaining what's at stake. On Vormir, Natasha Romanoff and Clint Barton fight over which of them will die for the Soul Stone. Natasha wins the argument by losing the fight, and dies.

Nebula is heavily cybernetic — Thanos replaced parts of her body each time she lost to Gamora in combat. Her systems are networked, which means the 2014 Nebula and the 2023 Nebula share memory access when in proximity.

In 2014, past-Nebula involuntarily accesses present-Nebula's memories and sees the Snap, Thanos's death, and the entire plan. Thanos extracts it from her. Past-Nebula then swaps places with present-Nebula and travels forward as a spy. Present-Nebula eventually kills her.

Stark and Rocket build a new Gauntlet in the present, in 2023, using the six Stones retrieved from the past. Banner wears it because gamma radiation gives him the best survival odds; it permanently damages his right arm.

The returned reappear exactly where they vanished from, in 2023, having experienced no time at all — Banner explicitly wills it that way.

Clint isn't involved in building it; his role in the heist was Vormir, and in the battle he carries the Gauntlet across the field.

A 2014 Thanos follows them forward and attacks. The final battle assembles every surviving character in the franchise.

Tony Stark takes the Stones and snaps Thanos and his entire army out of existence, and it kills him. His funeral closes the Infinity Saga.

There are two different Thanoses here, which is why Thor beheading him in the opening settles nothing. Thor killed the 2018 Thanos permanently at the start of the film. The one in the final battle is the 2014 version, pulled forward by Nebula's neural link — he has never snapped, never held the Stones, and is arguably more dangerous for it.

Stark's snap takes only Thanos and his army because the Gauntlet does what the wearer wills. Thanos willed "half of all life"; Stark willed "Thanos and his forces." Same tool, different instruction.

His army was the Chitauri, Outriders, and Black Order — a fleet, not half a world.

Steve Rogers returns the Stones to their original moments — and then stays in the past, living a full life with Peggy Carter, returning as an old man to hand the shield to Sam Wilson.

That handover is the film's final scene: an old Steve on a bench by a lake, asking Sam to try it on. Sam accepts and says it feels like it belongs to someone else.

Each Stone goes back to the exact instant it was taken, so no branch forms:

• Space (Tesseract) — 1970, Camp Lehigh
• Mind (scepter) — 2012 New York, back into HYDRA custody
• Reality (Aether) — 2013 Asgard, back into Jane Foster
• Power (Orb) — 2014 Morag, back into the temple
• Time — 2012 New York, to the Ancient One
• Soul — Vormir, 2014. The film never shows this. Natasha does not come back, and the mechanics of returning a Stone that cost a life are never addressed

He also returns Mjolnir to 2013 Asgard.

He cannot stay in the past cleanly — that is the honest answer.

By the film's own rules, living in the past creates a branch, so the Steve who lived with Peggy did so in a branched timeline and crossed back over as an old man. The Russo brothers have said this.

Co-writers Markus and McFeely have said the opposite: he was always there, in the main timeline, all along.

Marvel has never reconciled the two accounts.

With Chris Evans confirmed for Doomsday, whichever answer that film picks will probably become canon retroactively. Don't over-invest in explaining it before December.

Thor abdicates, names Valkyrie king of New Asgard, and leaves with the Guardians — briefly "the Asgardians of the Galaxy."

He leaves them early in Thor: Love and Thunder after a short power struggle with Quill over who's in charge.

Gamora does not come back to life. The one who died on Vormir is permanently dead; the Soul Stone sacrifice is irreversible.

The Gamora who is alive is the 2014 version, pulled forward with 2014 Thanos and stranded in 2023 when he's erased. She has no memory of the Guardians, no relationship with Quill, and finds his grief for a version of her she never was intensely irritating. Guardians Vol. 3 is largely about Quill accepting that.