With writer Roy Thomas back in the driver's seat following Gerry Conway's twenty-month stay on
Fantastic Four, artist Rich Buckler continued to make his mark on the title, handing both writers a number of successful tales to work with in a run which lasted over two years (though taking a break for a few issues). One of the earliest of those tales was just after Thomas had re-dipped his toes in the FF's waters by joining Len Wein to wrap up
the Dr. Doom/Silver Surfer plot which had entangled the team; from there, Thomas moved to guest-starring the uncanny Inhumans, along with a villain who had the misfortune of crossing paths with
one of the FF well over a decade before.
In the 1975 two-part tale, Zemu is dusted off and instead reintroduced as "Xemu," though you can continue to pronounce them the same, courtesy of the dizzying spin applied to the error by the letters page armadillo tasked with explaining it away:
(TBH, I happen to prefer "Xemu," though I can't bring myself to high-five the writer of that response when they couldn't cough up a simple "Oops" and leave it at that.)
Yet aside from the threat Xemu poses, in the spirit of FYI there are a number of takeaways from this story which are notable. For one, it marks the end of Medusa's lengthy stay in the book as a member of the FF, instated by Thomas as a replacement for Sue Richards just after the team helped the Inhumans come to terms with their personal shame in the form of the construct called Omega; in addition, Medusa's departure not only coincides with Sue's decision to return to the team, but also with Johnny Storm's decision to return to his original blue costume, having adopted the costume colors of his namesake, the android Torch, at the same time Medusa had decided to join the team. (Though Johnny's later decision to do an about-face on his costume choice actually had more to do with the real-life editorial decision implemented to avoid confusion in regard to the reappearance of the original Torch in
The Avengers.)
On a more humorous note, Ben Grimm, the Thing, once more is cajoled into attending the opera with his lady, Alicia Masters--and as we can see in a comparison with a prior story from 1963, the circumstances he encounters
after the performance are equally disagreeable.
While Johnny finds that, where women are concerned, clothes don't necessarily make the man:
And do you remember when Sue was toying with the idea of becoming a private eye?
A line of work she appears to have a talent for, as seen in her 2019 series where she flies solo as a secret agent--an occupation made retroactive to shortly after she
gained her force field powers. But the scene actually appears to be more of a nod to recent letters that wanted Sue to be more of a force in her own right post-reconciliation with Reed, with one letter's response hinting at a new development for her: "...in the next issue or two, ... you'll see Sue begin a whole new career--the last one you ever thought she'd pick!" Apparently toying with the idea was as far as it went.
Other items of interest include the fact that the Baxter Building has had a secret entrance all this time, which either Quicksilver, the Inhumans, or their foe have knowledge about:
It also turns out that Quicksilver is now considered an Inhuman, by decree and by himself:
Yet as to the main story, regrettably you'll find that it lifts a good deal of its content from
an earlier FF two-parter from 1969 while simply replacing the threat of Maximus with
Zemu Xemu. Though where Maximus achieved his goal from the use of hypno-potions, Xemu, while no stranger to deposing rulers through the use of force, makes good use of dimensional transport to bypass any perimeter defenses which the Inhumans have in place and basically take the royal family by complete surprise.