"Reunion".
Following last issue's breather episode, the X-Men would embark on one of their most complicated and famous plot arcs...In Space!. Chris Claremont is joined by a three person artistic team of Dave Cockrum, Bob Wiacek and Josef Rubinstein to tell a complicated story.
Cyclops and Storm are practicing superpowered handball in the gymnasium, and after a few pages of setting up their character dynamic, we are interrupted with Corsair of the Starjammers making an emergency landing on earth, and then interrupted again with the other X-Men setting up shop on Magneto's island from a few issues back. But rather than jumping around between subplots, we are actually going to pick a story and run with it for the rest of the issue.
The spaceship crashes on the grounds of the X-Mansion, and when Storm and Cyclops find Corsair he dramatically announces that he is Cyclops' father---followed by them being attacked by the Sindri, an alien race of spider like creatures who can merge together to form a gigantic flying airplane. Cyclops, Storm and Corsair fight them off, fleeing in the Blackbird away from the now, again, destroyed mansion. What follows is an improbable dogfight as the Blackbird flies under the Triborough Bridge and between the skyscrapers of Manhattan, while pursued by a living spaceship made of conjoined aliens...while also contemplating and arguing their morality and interpersonal relationships. Finally, after forcing the Sindri to disintegrate into individual creatures, Corsair sets off an explosion, killing them all, which offends Cyclops' sense of morality. The story ends with the dual problem of Cyclops emotional distance from his father, and of the revelation that all of these alien attacks are due to instability in the Shi'ar Empire, which will lead in the next issues to the X-Men flying into space and exploring galaxies.
There are a couple of things of note going on here. The first is that despite the fact that the X-Men of this era were usually remembered for their social commentary and stories set in the "real world", Chris Claremont wrote some of the greatest space opera stories in the Marvel Universe, and also could write straight adventures, as we have a supersonic airplane chase through Manhattan. On the other hand, we do start having more angsty interpersonal (and intrapersonal) conflict, and when the thought bubbles started popping up mid-gunfight I wanted to scream "not now! focus on the alien invasion, not on your sense of doubt and betrayal!". I do wonder if when John Byrne was scripting, some of Claremont's wordiness was curtailed. And finally, it is interesting that this issue focuses on Cyclops and Storm. A few years later, Wolverine would become the most obviously popular of the X-Men, but so far, he has been more of a supporting character than the star.