WARNING: The following contains spoilers for Dark Ages #1, available now from Marvel Comics.
As its title implies, Marvel's Dark Ages explores one of the darkest worlds in the Marvel Multiverse. While a teaser for the alternate reality event series teased a world where all electrical devices failed, that's only one aspect of a much more dire threat that threatened to tear the world apart.
Dark Ages #1 by Tom Taylor, Iban Coello, Brian Reber, and VC's Joe Sabino) begins with a series of quakes that originate from the center of the Earth. As Moon Girl and Reed Richards struggle to gain an understanding of what is happening, Uatu the Watcher appears with an explanation. As he tells it, a powerful cosmic being called the Unmaker was imprisoned within the Earth millions of years ago, and it just started to break free of that prison.
According to Uatu, the creature imprisoned within the Earth is a massive living machine that was created for the purpose of protecting the universe from entropy by way of consuming black holes before they could destroy the living matter of the cosmos. However, the machine was corrupted by consuming so much negative energy over the course of thousands of years, and it started to destroy everything that it encountered.
Eventually, the threat of the Unmaker became so great that an even greater cosmic being, the Living Tribunal, intervened. After defeating the living machine, the Tribunal placed it in a state of sleep and imprisoned it within the core of the Earth as it was originally forming. Now, eons later, the Unmaker awakened from its forced slumber and fought to free itself, which would inevitably destroy Earth in the process.
Even though some of Marvel's strongest heroes are ultimately successful in taking the Unmaker down, they take heavy casualties in the process and ultimately release a force that is almost as destructive as the Unmaker himself. While cosmic entities like the Celestials have been said to have a hand in Earth's creation for decades, the Unmaker twists that now-familiar narrative on its head, turning it into an uncaring, apocalyptic nightmare buried deep inside the Earth.
While it is still somewhat unclear where the Unmaker came from or who created it, the Unmaker serves as the ultimate cautionary tale of an automated guardian breaking bad, not unlike the DC Universe's Manhunters. Given the sheer destructive power and cosmic importance of the Unmaker, his presence within Earth also offers a potential explanation for why the Earth has found itself drawing so much attention from the far corners of the Marvel cosmos.
Although the threat of the Unmaker is seemingly dealt with by the end of the issue, death is never the end in the Marvel Universe. And with Marvel's heroes and society as a whole devastated by the loss of electric technology, there's no telling if they could be ready for another round with the Unmaker.