This story is set immediately after Balder was shot with mistletoe, and the footnote places in the middle of THOR #275. As Balder lays fatally wounded and Ragnarok approaching, Thor lashes out in anger, smashing a chair. He tells Sif that he does not wish to be violent within the halls of Asgard, so he needs some time by himself. Thor wanders into the presence of Mimir, the fiery Well of Wisdom that is all-knowing.
Mimir recounts his origin: Odin surrendered Mimir to the Vanir as a hostage during their ancient war, only for them to execute him and send his now-prophetic severed head back to Odin, who turned him into an eternally burning well of fire. Mimir hates Odin, and therefore Thor, but he states that he has his own reasons for answering their questions. Thor then asks if Midgard will be destroyed along with Asgard if Ragnarok comes. While Thor believes the realms are linked, he is also aware that many other pantheons exist who also believe that their fates are linked with Earth’s. Mimir agrees to tell Thor how the Earth will end. He then recalls that Thor has forgotten an important chapter of his life that occurred a millennium ago, so Mimir tells the following tale:
After a young and headstrong Thor learns that he can not advance Asgard’s domain through conquest (THOR ANNUAL #5), he sets off for Midgard to try to extend the realm in other ways. As he flies over a remote mountain range, Thor hears a mysterious voice calling to him from a sealed cave. Thor breaks into the cave and finds a huge being imprisoned within. The being, who reveals himself to be Dromedan, attempte to entice Thor into freeing him from his bonds and the helmet that covered his head. After breaking free from Dromedan’s mental command and realizing that he was evil and incredibly powerful, Thor once again seals the cave and continues on his mission.
Spotting a tribe of savages, Thor lands and demonstrates his godly abilities. He is puzzled that the savages attack him instead of worshipping him. Just then, Thor looks up and sees four humanoid beings flying overhead—one of whom, Druig, dives to attack him with great force! Thor quickly overpowers Druig, then hurls Mjolnir to dispatch Ajak, one of his companions who came to his aid. Viranko and Valkin then land and introduce themselves as Eternals. Viranko admits that Druig had attacked unprovoked, and suggests that instead of fighting, they should converse on a mountaintop overlooking the village.
Thor and the Eternals have a hard time identifying each other, as the Eternals have only heard about Earth’s mythological gods, but did not believe they existed. Viranko explains how the First Host of the Celestials came to Earth eons ago, and created three races from the ape-like creatures that existed at the time: the humans, the Eternals, and the Deviants. Eventually, the evil Deviants came to rule the planet, and even fought back against the Celestials when they returned during the Second Host. As a result, the Celestials destroyed all Deviant and human cultures, leaving them to rebuild civilization once again. Thor reveals that he had seen Dromedan, who the Eternals recognize as one of the Mutates, an evil race created by the Deviants.
Thor becomes fast friends with the Eternals and spends some time traveling among them as they civilize Earth’s primitive tribes— notably the Maya and the Inca. As Thor and the Eternals travel through Mesoamerica, Druig remains alone in the Eternal city under the pretense of continuing his research. In reality, Druig plans to free Dromedan, believing that he can control him in order to take over the world.
When Thor and the Eternals eventually return from their civilizing missions, they are shocked to see that the locals had already begun building great pyramids. They also see Druig, standing frozen atop a mountain peak with a green energy around him. He had been overpowered by Dromedan, who unleashes two mighty beings to challenge the Eternals: Tutinax, another Mutate, and Thunder, a deity created from the subconscious minds of the savages. Thor takes on and defeats Thunder while the Eternals struggle against Tutinax.
As Thor joins the battle against Tutinax, Dromedan attacks again. The events of the battle are so great that they enter into the myths and legends of the indigenous tribes as the “Four Cataclysms.” Dromedan unleashes a giant worm against the warriors, which is only defeated when Virako soaks himself in radiation from the atomic core of their ship and flies directly into the maw of the worm. Both Viranko and the worm are destroyed, exploding into energy and light.
As the remaining warriors attack Dromedan, the Eternal Ajak recovers the helmet that had been used to suppress Dromedan’s powers in the cave. Flying above, Ajak drops the helmet back onto Dromedan’s head, and Thor quickly seals it back onto Dromedan by hammering it shut with Mjolnir. As the battle finally ends, a great shadow suddenly descends over the land—the Celestials have returned! Fearing that Thor will try to do battle with this Third Host, Valkin erases Thor’s memory and sets him on his way.
Back in Asgard in modern day, Thor asks Mimir why he has shown him all this, since it was so long ago and so disconnected from Ragnarok. Mimir reveals one final image, of Earth today: the Fourth Celestial Host has come, and Arishem will decide within half a century whether the Earth will live or die. Without answering, Thor leaves Mimir, the story continuing in THOR #275.