Also of note: this is one of the only Big Bang comics to feature just one story. If anything I'm reminded of the Metal Men, as this is an "amazing three-part novel" or "novel-length adventure" that would easily be a huge three-month, 20-title crossover today.
So, okay, this is technically a reprint of a story from the original Caliber Comics run, but whatever. Cover art by Curt Swan, though. I don't see why Golden Age Ultiman doesn't merit a credit on the Knights of Justice side of the cover, or where the Silver Age Knight Watchman is, though.
The Silver Age Beacon first appeared in this story, but the Human Sub had his origin story in Big Bang Vol. 1 #2. Basically, he's Dr. Noah Talbot, an aged scientist who designed a robotic full-body prosthesis that he was forced to transfer his own mind into as he suffered a heart attack. The robot body is powered by "hydro-glycerin" and needs to be submerged in water at least once an hour. His sidekicks are his granddaughter Mora, alias the Moray, and Bubbles, an amphibious chimp with hydro-glycerin for blood.
I'm guessing Swan's pencils for the cover were finished before they decided to change him to the Atomic Sub. Or even before they did the first Human Sub story; the first page has Swan's original art, with a totally different looking Human Sub. Cyclone's also an all-new character, but there's not a lot to say (or know) about him until the Whiz Kids get their own stories.
And see, look, Golden Age Knight Watchman isn't even in this, jeez.
The story kicks off with the Blitz running late to an appointment at Round Table of America HQ. Apparently he lives in the Southwestern US, because that's where he's coming from. HQ is at "Capitol City" on the East Coast. So he really kicks it into high gear to make it in time, but once he gets through the door of the Hall of Heroes, he sees something so shocking he alerts the rest of the RTA for help. But when help arrives, the Blitz isn't there -- at least, not their Blitz!
As you can no doubt imagine, a fight breaks out, and oddly enough the Atomic Sub seems the most eager to teach the 'phony' Blitz a lesson. Yeesh, take it easy, old timer. Incidentally, the Beacon's powers appear to be similar to her Golden Age counterpart's; that thing in her hand gives off light in different colors, each with its own effect. Kudos for creativity, I think most people would have just given their ersatz Lantern regular construct powers.
The Blitz runs rings around the RTA members, but Ultiman manages to clock him one and knock him out. Almost immediately, Dr. Weird, the Spectre analogue, pops in to say he knows where the "real" Blitz is. From the other heroes' reactions, it looks like they've never met Weird before.
Naturally, the Silver Age Blitz is at the Hall of Heroes on another Earth, where he's getting manhandled by the Knights of Justice.
That blast knocks the Blitz right out, as well it should, but as before, Dr. Weird appears before the Knights of Justice. I'm referring to both groups as though they're the full team, but come on, these are abbreviated versions of the KoJ and RTA.
It turns out Dr. Weird is talking to both groups at the same time, with each group not even knowing the other figures into it (except the Blitzes, I guess). The Beacon says that Dr. Weird is telling the truth, according to his power crystal; I guess he's the truth-detector because he's the only one with any super-equipment akin to WW's lasso.
Dr. Weird exposits that there are two Earths, which split off from each other in the early 20th century: Earth-A, where it's 1965, and Earth-B, where it's 20 years earlier. He also makes note of the two Blitzes, two Beacons, etc., without really explaining what causes that. So it turns out someone opened a portal that the Blitzes accidentally traveled through, and if it isn't closed soon, both worlds are doomed. Weird has it stabilized for the moment, but can't keep it up much longer, and tells of machines on each Earth that are widening the portal. Both Ultimen independently decide to go give Weird a hand.
Meanwhile, apparently the other members of both teams (and the displaced Blitzes) know where to go to find their machine. I'm gonna go for the No-Prize and say Weird gave them the information telepathically. The KoJ arrive in Paris, where a huge robot gorilla and a crazy looking machine are on top of the Eiffel Tower. The Blitz rushes at the robo-ape, but disappears after it swats him away. While Venus and Thunder Girl distract the robot, the Beacon uses his red force beam to amplify his strength so as to destroy the machine. He does this by simply punching it, causing it to explode. When the dust settles, only Thunder Girl is conscious, and the Beacon is missing.
The RTA head for the Statue of Liberty's torch, which houses their world's portal machine thing. The Beacon is the first to notice it, and I'm having flashbacks to #4, when the Golden Age Beacon fought guys on Liberty's torch.
The Blitz runs afoul of another robot gorilla, identical to the one seen a second ago, and disappears after is blasts him with a ray. The Beacon tosses it into the water with her yellow levitation beam, and the Atomic Sub swims toward it to finish the job. Suddenly, the Beacon vanishes into thin air herself!
It turns out that the Blitzes and Beacons were simply pulled away by Dr. Weird, who needs more power to keep the rift stable. That this happened in conjunction with their fighting the robo-apes appears to be a simple coincidence. The Beacons join hands with their respective Blitzes, and discover that giving their energy to Dr. Weird hurts like crap. The Beacons are forced to sap power from distant stars in order to provide enough for Weird to go on.
Meanwhile, a mysterious cloaked figure supercharges the Earth A robo-ape, which revives, knocks out the Atomic Sub, and grabs the machine before the Knight Watchman can take care of it. The Knight Watchman decides to call in reinforcements in the form of the Whiz Kids, who find the mystery baddie's lair on Ellis Island easily enough, but run into trouble fighting the robo-ape... until Bubbles starts messing around
After this odd scene, the robo-ape comes to its senses and knocks Bubbles into Kid Galahad, who accidentally crashes into the machine, sending both of them... somewhere when it explodes. That "somewhere" was Earth B, where they're met by Venus and Thunder Girl. Thunder Girl sees Bubbles' costume and realizes who's behind all this, and resolves to go to Earth A via the still-intact device in order to stop them.
Meanwhile, on Earth A, the big bad guy is holding both worlds hostage with the device, which is really more of a bomb and seems to be okay after colliding with Kid Galahad and Bubbles. At some point the Knight Watchman and Atomic Sub showed up.
Suddenly, Thunder Girl bursts through a small explosion, having traveled via the device as mentioned previously. She grabs the villain, revealing him to be her archenemy Dr. Binana, the talking chimp. Binana says he created the portal to plunder both worlds, but is willing to settle for destroying them both! After Binana activates the bomb, which is of course on a timer, the Atomic Sub grabs it, flies over the sea with his jetpack, and tries to bury it as far underwater as he can. Shortly after he leaves, the Knight Watchman gets word from Kid Galahad that they've disarmed the bomb on their end. This eliminates the threat to both worlds, as without the second bomb this is just any old bomb.
However, the Atomic Sub couldn't get far enough away from the explosion in time, and died trying to save two worlds. Everyone is automatically returned to their home Earth... except for Thunder Girl, who remains on Earth A. Dr. Weird says this has to do with her power source and origin, as she's a mystical being of two souls and whatever. We end on a somber note, with funeral proceedings dedicated to the Atomic Sub -- even on Earth B, which he'd never set foot on.