Synopsis
This issue mainly ignores the ongoing Kang Dynasty War in favour of finishing the Triune Understanding plotline (simmering since #13, or possibly Triathlon's 1st app in #8).
It begins with the 1st of many flashbacks narrated as if they were myths. The Trion were 3 beings supreme in their dimension. Ages ago they expelled all evil from within themselves and imprisoned it in a dark sphere. But 1 fragment of that evil escaped into the Marvel dimension where it took the form of a large black pyramid and began journeying through space.
But at the current time in our dimension the time-travelling Kang The Conqueror is threatening to conquer Earth. Captain America, Jack Of Hearts, Photon and Scarlet Witch tried to attack his orbiting Damocles Base but failed. Now we see robots from the Base scooping up the 1st 3 of them floating in space, but they are prevented by 2 kinds of blast and some arms with familiar wristbands. They awake in a quantum bubble with Living Lightning and Quasar, and learn that Kang's robots took Scarlet Witch before the duo could stop them. And they too can't penetrate Damocles' forcefield. Cap wants to get back to the War, but Wendell Vaughn says there might be a bigger problem.
In the 2nd flashback we learn that the Marvel universe reacted to the evil pyramid by creating 3 'antibodies' in the form of small white pyramids which also began travelling. The 2nd of these pyramids was picked up by a passing Skrull spaceship.
Steve Rogers still wants them all to go fight Kang, because Quasar doesn't *know* that the menace he and Miguel Santos found is worse. But then another party enters the discussion in the form of a spaceship containing Jonathan Tremont of the Triune Understanding plus some other Avengers. Our bunch are invited inside.
Flashback 3:- In the Naga hills in India there were 3 young brothers, 1 wise, 1 strong and the youngest a charmer. But the older 2 died of a sickness, and the youngest suffered survivor's guilt. And the segue into the next section makes it plain that the survivor was ...
... Jonathan Tremont, leader of the Triune Understanding. Cap's gang meet up with Firestar, Justice, Triathlon and Vision in the Triune's spaceship. And Tremont points to the giant pyramid in space as the threat they are out to counter.
The next flashback is in California where Chuck Chandler is out for a spin with his girlfriend Peggy Clark, with his crippled brother Hal in the back seat. But then the scene shifts to test pilot Chuck seeing a UFO which captures him and his jet. But he breaks free of the Skrulls, sets their craft to explode and escapes in the jet. However these were the Skrulls who found the white pyramid, and the explosion causes it to change Chuck. When he crashlands the plane he splits into 2 bodies, 1 red and the other green, which merge with brother Hal. After that Hal Chandler could manifest Chuck as the 3-D Man with his abilities tripled.
In the Triune spaceship Cap isn't happy with what's been going on - Iron Man sending Firestar and Justice undercover to spy on the Triunes, and Warbird and Vision getting Triathlon to take Vision to the Triunes for more spying, plus Tremont draining the lifeforce of his acolytes to power the spaceship. But when Quasar tells him the pyramid holds enormous power and is heading for Earth Steve agrees to go with the flow. Jonathan tells them that this is the Triple-Evil whose foretold coming was the reason he founded the Understanding. Quasar's quantum bubble gets the players to the dark pyramid, and something takes them inside.
In another flashback we see that it was Hal Chandler who married Chuck's girlfriend Peggy, and they had 2 sons also named Chuck and Hal. The boys grew up and left home. Later Hal left Peggy to answer a feeling that called him to the Himalayas north of the Naga Hills. A native guide accompanies him as he is drawn to a certain cave where they find the 3rd pyramid of light. And the guide, Jonathan Tremont, knocks him unconscious to take it.
Inside the black pyramid the Avengers experience hallucinatory wish-fulfilment lives. We see Jack Of Hearts being told by SHIELD that they've found a way for him to completely control his power, so he can life as a normal human without his armour. And also genetic scans have shown that he's not half-alien as he had been told. Miguel Santos has parlayed his Living Lightning role into a successful political career. And Vision is torn between a woman named Darby and his ex-wife Scarlet Witch who says she wants him back. But the synthezoid senses this isn't real.
We then pull back to aliens in the pyramid studying the captive Avengers and Triune members who have their heads in transparent pyramids. From the captives vocalisations we can tell *their* fantasies. Photon is elected Avengers Chairman again, Firestar sees the Avengers disbanded because they have attained World peace. Justice is having a Jewish wedding (presumably to Firestar). Quasar just gets to go home on Earth (he's presumably still self-exiling because of dangerous Ego The Living Planet within him). But what Captain America wants is to be free to defend Earth from Kang ...
... and he *does* break free, which snaps the others out of their dreams as well. An alien tries to calm them and explain what's happening in fractured English. He claims that they were scanning their minds for their fondest wishes so that they could make them reality. But what Cap wants is to get back to the war on Earth. He tries to leave and that's when the aliens transform into more menacing insectile forms. And the chamber they are in disintegrates to reveal hordes more of the aliens surrounding them. But instead of a physical attack, their minds are filled with images ...
... which constitute the next flashback. The dark pyramid sailed through space radiating corrupting evil. Many alien species fought against it but it took their best warriors and embedded them in dreams unto death. Meanwhile their corrupted bodies became soldiers for the pyramid, and their spaceships added to its armour.
Then the Avengers and Triunes fight back like those before them. The battle goes well until the enemy warriors adapt to their powers and skills. Then Jonathan Tremont calls upon his brothers, and Lord Templar and Pagan spring forth to renew the fight. (And it becomes clearer to the Avengers how Tremont has been manipulating them all along.)
Cue another flashback. Jonathan had (somehow) kept the spirits of his dead brothers close to him. He could sense the 3rd white pyramid was nearby, but he needed the other pyramid holder Hal Chandler as a divining rod to find it. Now he used the pyramid to call forth his brothers, and as the 3-in-1 they would amass power to face the oncoming Triple-Evil (which the pyramid obviously told him about).
The Avengers aren't happy about accepting aid from their earlier foes Pagan and Templar (who of course are genuinely Tremont's brothers). Meanwhile something surfaces within Triathlon and he remembers Jonathan hitting him from behind in the mountains ... but that's Hal Chandler's memory.
The continuing flashbacks show Jonathan Tremont coming to America and forming the Triune Understanding. Meanwhile his pyramid gave him a sense of the dark pyramid approaching. And he saw it opposed by an alien champion who possessed the 1st white pyramid. But he too fell and the dark pyramid gained that shard of light. 1 white pyramid was not enough to defeat the dark, so Tremont would need 2.
We see that he already Hal in suspended animation. Jonathan and his brothers formed a triad to fully use the 3rd pyramid, but Hal and Chuck were only 2 and so could only access a fragment of its power. Then disgraced athlete Delroy Garrett came to the Triunes seeking illumination, and Tremont sensed a spirit kindred to the Chandlers. He suffused Delroy with pyramid power from the hidden Hal, and gave him a costume as Triathlon.
Now Delroy remembers it all and accuses him of only seeking power. Jonathan replies that he did good along the way, but it is true he needed all the power he could get to defeat the Triple-Evil and save the Earth. However he then switches over to evil supervillain mode and says that it will be only right that he then rules the World he has saved. He is suffused in a glow of power (presumably power we saw him in earlier issues absorbing from the faith of his followers). But now he needs more, which he takes from the Triune members that came with him, reducing them to skeletons. And now in full rant mode he takes the lifeforce of his brothers Pagan and Templar. And the alien servitors of the dark pyramid fall back before him.
Lastly Tremont seeks to take the power of the 3rd pyramid from Triathlon. Delroy dodges but gets tagged at last. Tremont rips the 3 component people apart to free the pyramid for *him*. But the 3, ie Triathlon, 3-D Man and Hal, flee together and find the 1st pyramid in the body of the alien champion. They take it and it combines with their 2nd shard, which makes them twice as powerful as Tremont. It is *they* who rip the 3rd pyramid from *him*. Chuck, Delroy and Hal expand to dwarf the black pyramid and blast it from without.
Now the mythic voiceover describes the titanic battle between good and evil. Because our trio's hearts are pure they dismiss the temptations of the Triple-Evil and drive the darkness out of the large pyramid.
Quasar imprisons Tremont in quantum handcuffs. The 3-in-1 tell the Avengers that the pyramid still has all the power stolen from those the darkness conquered, and they may be able to use it to get back to Earth. But Vision has picked up radio messages from Earth and tells them that while they've been away the planet has surrendered to Kang.