Earth-203 and New Gotham is shown complete with red skies, as Huntress from the Birds of Prey TV series, runs across rooftops before the anti-matter wave hits and the world is destroyed.
Aboard the Waverider over Earth-1, the Monitor convenes the heroes in his quest to find the remaining three Paragons as the Atom repairs his Paragon detector. They are joined by Flash and his team, and all agree to save as many people as possible from the other Earths, bringing them to Earth-1 which calculations show will be the last to be destroyed. With the Paragon detector fixed, Martian Manhunter is revealed as the Paragon of Honor, Flash the Paragon of Love, and Dr Ryan Choi as the Paragon of Humanity.
John Diggle, Green Arrow’s best friend, arrives and is angry at the death of Arrow, but is willing to take part in the trip to Purgatory to retrieve Oliver’s soul. White Canary also tells him that Diggle’s wife Lyla – aka Harbinger – has gone missing. When they ask the Monitor where Lyla is, he suggests that she could be with the Anti-Monitor.
The Monitor tells the other heroes that the battle against the Anti-Monitor is why he has been testing them. Cisco tracks the source of the anti-matter wave and he and Frost head off to deal with it, but not before the Monitor returns his Vibe powers to him. Vibe and Frost find the subterranean dig that Nash Wells has been working on, only to find that Nash has become Pariah.
He explains that his original plan to find and kill the Monitor was subverted by the Anti-Monitor and Pariah is now under his control, the Anti-Monitor using him to gain a foothold in the Earth-1 universe. Vibe uses his powers to access Pariah’s memories in order to get access to the Anti-Monitor’s lair.
On the Waverider, Supergirl discusses using the Book of Destiny with Lex Luthor to restore the destroyed Earths. Batwoman decides to help her, despite the risks.
On Earth-666, Constantine, Mia and Diggle meet with Lucifer who provides them a way into Purgatory but warns them they will have a limited amount of time there, and if they don’t escape, they will remain there forever. Constantine takes them to Purgatory which looks like the island of Lian Yu to find Green Arrow.
Flash joins Cisco, Frost and Pariah as they try to get to the source of the anti-matter wave to stop it. They find an anti-matter cannon being powered by the Flash of Earth-90. Pariah reveals that the Anti-Monitor has captured Flash-90 and forced him to run on a treadmill, feeding the anti-matter cannon. Vibe is able to get Flash-90 off the treadmill and stop the cannon but he tells them that he has to get back on – the cannon has a fail safe which means it will erupt destroying all remaining Earths if the Flash were to be removed.
In Ivy Town on Earth-1, the Atom, Elongated Man, and Iris meet Ryan Choi who is a big fan of the Atom’s alter ego Ray Palmer. They ask him to help them save the universe, but Ryan rejects the idea of being a hero and instead heads home to his family.
Lois watches the destruction of Earth-73 and speaks with the Monitor, mentioning there are only seven Earths left. The Monitor reveals that he had a family at one time and regrets not spending time with them. Superman-96 briefly and bemoans the fact he could not save the people there.
Back at the anti-matter cannon, the heroes are surprised when Black Lightning appears, Pariah having saved him from (possibly) Earth-73’s destruction. The Flash convinces Black Lightning to help them by containing the excess energy from the cannon.
Supergirl and Batwoman argue about using the Book of Destiny to restore the Earths, with Batwoman talking her out of using it.
The two Flashes speed up their personal fields to slow time for the others, allowing them to discuss how to defeat the anti-matter cannon, with the Flash realising that this is what he has been running towards – that this is when Flash vanishes in Crisis, as foretold by the newspaper in the time vault. Flash realises that by reversing the treadmill, it will redirect the anti-matter wave, destroy the cannon, and free Pariah from the Anti-Monitor’s control.
In Purgatory, the heroes are attacked by Green Arrow who struggles to remember them before embracing them.
Iris tries to convince Ryan that he doesn’t need to be a superhero to help, and he agrees to help. The Atom informs them that six more Earths have been destroyed, leaving Earth-1 as the final one.
The Flash says goodbye to Cisco and Frost, but Flash-90 temporarily steals his speed, taking his place, saying that the Monitor said a Flash had to die in Crisis, but not which one. Cisco vibes Flash-90 back on to the treadmill and as the others escape, Flash-90 runs, reversing the treadmill, vanishing into nothing as the cannon explodes and the anti-matter wave dissipates before it hits Earth-1.
Green Arrow and the others are met by Jim Corrigan who passes the Spectre force to him, telling him that only he can light the spark to save the universes. Constantine, Diggle, and Mia return to the Waverider without Green Arrow.
Flash comforts Black Lightning aboard the Waverider as he mourns the loss of his family.
Batwoman and Supergirl talk and Batwoman offers her the Kryptonite that she took from Bruce Wayne of Earth-99, saying that she hopes she would never use it. Supergirl asks her to keep it, saying she has the courage that she never will never have to use it.
Iris, Atom, Elongated Man, and Ryan return to the Waverider, and the whole team are surprised when Harbinger reappears, apparently with no memory of where she has been. Flash realises the Anti-Monitor is still controlling Harbinger and he speaks through her, threatening to end the heroes. With everyone except Pariah and the Monitor incapacitated, the Monitor attacks Harbinger but is defeated. As Pariah watches, a new anti-matter wave rises and destroys Earth-1, leaving only the Waverider.
Pariah steps forward and sends out beams of light that strike the seven Paragons, causing them to vanish, just before the anti-matter wave hits the Waverider, disintegrating the remaining heroes.
The Paragons arrive at the Vanishing Point, a place outside of time. Superman-96 falls to the floor as red lights bursts from him, leaving Lex Luthor in his place. He reveals that having seen this event in the Book of Destiny, he rewrote the scene so that he would take Superman-96’s place.
 – Earth-203 is likely a reference to the original Birds of Prey series which ran from 2002 to 2003.
 – Earth-666 is a very lazy way of designating the Earth upon which Lucifer lives; 666 is the Number of the Beast according to the Biblical Book of Revelation and has long been used by writers to signify something bad.
 – Earth-90 is named after the original air date of the ealier Flash TV series.
 – Earth-73 is only seen on a Waverider monitor screen so nothing to give us a clue as to why it’s numbered as such.