We were not prepared for part three of “Crisis on Infinite Earths.”

This latest chapter, on CW’s “The Flash,” touched on elements of the now classic tale and then swerved off in directions unexpected, the shocks multiplied by appearances from several veterans of other DC shows.

Sure, we knew John Wesley Shipp would be reprising his role as the original Flash, but who expected the original Birds of Prey? And Lucifer! Freaking Lucifer, just as smarmy and seductive as can be.

And that was Ashley Scott reprising her role as the Huntress from the short-lived, vastly underrated 2003 “Birds of Prey” series. The unseen Oracle she was communicating with? Co-star Dina Meyer.

Too bad we didn’t have more time with them because that energy wave wipes out Earth-203 and all of New Gotham with it.

Ironically, later in the hour, there was a commercial for the “Birds of Prey” film, which is nothing but a Harley Quinn solo in disguise. It may be fun, but it’s not the real deal. If you are ever inclined, get the DVD collection of the first and only season of “Birds,” but 14 episodes. Its biggest sin was debuting before the Modern Age of Superheroes now reigning over TV and the box office.

On the Waverider, Ray manages to get his detector fixed and two more Paragons are identified. Martian Manhunter represents honor, the Flash, love.

Isn’t that all convenient?

But wait! The seventh and final one is physicist Ryan Choi, at Ivytown – Ray’s old stomping ground. Our heroes must recruit him before it is too late.

The Monitor seems to enjoy eavesdropping, and after Cisco makes another canny deduction, he insists on giving him a gift, despite his protest – the return of his powers.

“Vibe must live again,” he says, so he too may serve his higher purpose. Turns out the Monitor is right on that.

Constantine brings Mia and Diggle to Earth-666 to find the one person who can help them retrieve Oliver’s soul from purgatory – Lucifer Morningstar (actor Tom Ellis), star of his own Fox and now Netflix series and now officially part of DC Arrowverse canon, and that sound you hear is fandom howling with joy.

Lucifer flirts with Mia, seems to ogle Diggle, and snarks at Constantine.

Because he owes the mage a favor, he gives them a playing card, a pass into purgatory. If they can’t retrieve Oliver before the card fades, they will be trapped with him for all eternity.

And after “Lucifer” ends next season, CW should beg him to join “Legends.” Yes, it’s crazy and I don’t care.

Purgatory for Ollie turns out to be Lian Yu, where he is amnesiac – for a moment, anyway. Diggle helps him to remember himself. Their reunion is derailed by the appearance of – what? – Jim Corrigan, also known as the Spectre, who tells Oliver he has another destiny and sends his pals back to the Waverider. This resurrection will not have a happy ending.

The Flash gang track the source of the antimatter wave – an antimatter cannon being powered by the Flash of Earth-90 (John Wesley Shipp).

Vibe, turns out, is just the hero needed to create a breach in the force field and freeing OG Flash. But the Anti-Monitor designed it with a failsafe, and it will destroy the other remaining earths unless he gets back on.

As the Flash gang try to figure a solution, Pariah arrives with a newcomer: Black Lightning, who is pissed about being kidnapped from his world.

No worries, Pariah tells him, his planet – and his beloved family – were all destroyed by that antimatter wave.

Hey, welcome to your first crossover, Jefferson Pierce.

Somehow in the midst of this mind-numbing news that he is sole survivor of his world, Black Lightning finds it in himself to get to the crisis at hand, channeling the energy of the antimatter cannon.

It’s but a temporary solution. Barry realizes this is the moment he’s been preparing for:

“It’s time for Flash to vanish in the crisis,” he tells his friends Caitlin and Cisco.

Only his speed can destroy that weapon.

Except it isn’t. The OG Flash steals it, just for a moment, reminding him the Monitor said the Flash must die in this crisis, but he didn’t say which one.

I don’t know, it’s been pretty clear since the debut of the “The Flash” in 2014 that this was his destiny, but far be it for me to argue with a celebrated guest star.

Cisco reluctantly opens another breach to allow OG Flash to return to the cannon, and in his final moments, the speedster thinks back to his beloved Tina McGee (Amanda Pays, in a flashback from the 1990 series). Then he runs right into oblivion, a hero to the end.

Supergirl and Batwoman spend their hour hashing out the wisdom of using the Book of Destiny to re-create Earth-38. Batwoman fingers her sliver of Kryptonite, but ultimately tries to give it to Kara. Kara refuses it, telling Kate to keep it with the courage to know she will never have to use it.

On Earth-1’s Ivytown, Ryan Choi is thrilled to meet his idol, Ray Palmer, but not so happy to learn of his great destiny. If the world is being destroyed, he must be with his wife and child. Drawing on her own sacrifices, Iris convinces him to go with them so that his wife and child can actually have a world.

Everyone reconvenes on the Waverider, and Lyla finally appears, claiming not to know where she has been all this time.

Then the Anti-Monitor speaks through her, warning that he plans now to end the age of superheroes.

Now I count at least four heroes with enhanced speed in the room (Flash, Supergirl, two Supermen) and yet everyone does that thing where they just gawk at the villain. Come on, Elongated Man, stretch and give her/him/them a bitch slap.

Nah. Lyla waves her hands and the heroes fall. Pariah can only watch as Lyla takes on and kills the Monitor.

The antimatter wave engulfs Earth-1. Only the Waverider remains, for mere seconds.

Pariah teleports the Paragons – Supergirl, Batwoman, the Flash, Martian Manhunter, White Canary, Kingdom Come Superman, and Ryan Choi – away.

The energy wave strikes and destroys the Waverider and all the supporting players of the CW shows.

So where are the Paragons?

At the Vanishing Point, Sara recognizes – a place outside time and space.

Before they can get their bearings, KC Superman collapses in agony – and vanishes – replaced by – Lex Luthor!

To the horrified heroes, Lex explains, when he had the Book of Destiny, he jumped ahead a few pages and figured destiny could use a rewrite. He scrawled his own name over Superman’s.

“What do we do now?”

That is just so evil.

Random bits:

Surveying the gathering of heroes, Elongated Man says, “Holy All-Star Squadron.”

“Ignore him. It’s his first crossover,” Killer Frost says.

The original Birds of Prey. The original Flash. The Superman of “Superman Returns.” All perished in this hour. For any longtime lover of DC, this was brutal. I’m suddenly glad we didn’t get a cameo from original Wonder Woman Lynda Carter. That would have been too much.

Wentworth Miller was back on hand as the unseen and utterly sarcastic AI of the Waverider. When the multiverse is re-created, he better be a part of it.

“Crisis on Infinite Earths” continues on “Arrow” Jan. 14, and a month is too long to wait.