Stan Lee and Jack Kirby's collaboration on Fantastic Four is legendary for being the foundation of the modern Marvel Universe and one of the longest-running collaborations in comics. Although they published over a hundred Fantastic Four stories, Stan Lee and Jack Kirby's final tale took decades until it was published in its intended form.
Lee and Kirby worked on 102 issues of Fantastic Four and six annuals before Kirby left the book. Afterward, however, there was still one lost adventure which took a while until reaching publication. This story was shelved until 1971's Fantastic Four #108, by Stan Lee, Jack Kirby, John Buscema and John Romita, Sr. In this issue, a considerable amount of Kirby's pencils from the lost story were reworked into a flashback tale.
Still, the lost issue of Fantastic Four had yet to be released in its intended form. It wasn't until 2008's Fantastic Four: The Lost Adventure, by Stan Lee, Jack Kirby, Joe Sinnott, Ron Frenz and Chris Sotomayor, that this final collaboration between Lee and Kirby was finally restored. Despite the best efforts to restore this issue in full, John Morrow, editor and publisher of the Jack Kirby Collector, noted how a few panels were missing from Kirby's original pencils. Even so, the lost issue was restored as fully as it could have been and released.
Fantastic Four: The Lost Adventure recounts an attack by a villain known as the Janus, Mega-Man, who wreaked havoc on New York City. Breaking into a bank vault, Janus surprisingly defeated the Thing and the Human Torch. A suspicious Mister Fantastic and the Invisible Woman went to Kansas to visit Reed's old college classmate, who was also named Janus.
Sue used her invisibility powers to plant a camera in Janus's house, before readers were shown that the Mega-Man was Janus's evil twin brother. The Mega-Man coerced Janus into enabling his crimes, by promising Janus to restore the full use of his legs. After the Mega-Man discovered the camera Sue planted, he used his power to destroy the Fantastic Four's monitor. With this deadly display of force, the Fantastic Four split up to fight the Mega-Man.
The Thing and the Human Torch barely survived the Mega-Man's attack on New York City, as he demanded that the city turn over their entire treasury within 24 hours. When the Mega-Man returned to Kansas, he was confronted by Reed and Sue. Mega-Man nearly convinced Janus to shoot Reed, but Sue disarmed Janus from behind. In the end, Reed used the Mega-Power device to restore the use of Janus' legs, and both Janus and his brother were taken by the police.
The original version of this tale was released decades after Fantastic Four #108, which reframed the lost adventure as a long flashback story within the context of the ongoing Fantastic Four series. There were several differences between both versions of this forgotten tale. Little things such as the presence of the Inhuman known as Crystal and baby Franklin Richards were absent from Fantastic Four #108.
The dialogue was also slightly altered and the story was a little shorter than in Fantastic Four: The Lost Adventure, too. For example, Fantastic Four #108 only saw Reed and Sue approach Janus's house once to confront him at the end of the tale. This version of the story omitted the sub-plot where Sue planted a mini-camera in Janus's house. This was quite different than in Fantastic Four: The Lost Adventure, where Reed was immediately suspicious of Janus and decided to spy on him. Instead, Janus asked Reed for help, triggering his suspicions in Fantastic Four #108.
Janus's house was also in Midvale instead of Kansas, making its location a bit more ambiguous than in Fantastic Four: The Lost Adventure. Most importantly, Fantastic Four #108 referred to Janus as the Nega-Man rather than the Mega-Man. This was largely due to the circumstances of Janus' creation. In Fantastic Four: The Lost Adventure, the Mega-Man was Janus' twin brother. Fantastic Four #108, however, revealed that Janus was experimenting with Nega-Power, which was connected to the Negative Zone.
During one of his experiments, Janus created his evil twin, the Nega-Man, who represented all of his evil thoughts and actions. In this altered version of the original story, Janus only aided the Nega-Man because he was afraid that, if he killed his negative counterpart, he would die. In the end, Janus seemingly killed the Nega-Man, making him a bit more heroic than in the original version of the story.
Janus's heroism also changed the Invisible Woman's role from the original tale, where she stopped Janus from shooting Mister Fantastic. All of Fantastic Four #108's flashback was centered around the return of the Nega-Man as well. Janus had broken into the Negative Zone, attempting to accumulate his Nega-Power and incidentally meeting Annihilus. This was a stark contrast to Fantastic Four: The Lost Adventure, which was entirely self-contained. Fantastic Four #108 was part of a larger storyline, while in Fantastic Four: The Lost Adventure, Reed was merely recounting the Fantastic Four's adventure to his friend, Dr. Claymore. While there were some important changes to the Fantastic Four's lost adventure, the original tale still stands more or less as it was originally intended.