The Defenders have a final battle against a mind-controlled Squadron Supreme and the Overmind!
The end of the Squadron Supreme-Overmind-Kyle Richmond-Null storyline, as well as a highly unusual coda. This issue bills itself as "one of the wildest Defenders sagas ever," and it certainly is in the running!
The Earth-S Kyle Richmond and the Earth-616 Mindy/Overmind finally explain Kyle's recent history. When the Earth-616 destroyed August Master's base several issues ago, Mindy and the other powerful psychics used their powers to come to this dimension, and tried to bring Kyle with them. However they were not used to their power, and accidentally brought the 616 August Masters along instead.
Meanwhile, the Overmind had mentally taken over the Earth-S Richmond, destroying his mind in the process. He decided to just use a puppet Richmond instead, and it was this fake Richmond that Masters shot earlier. However, Mindy found the now-mindless real Earth-S Richmond and filled his mind back with a copy of the mind of the 616 Richmond, who she loved. The Earth-S Richmond, who now has his mind back, can't forgive her.
The Defenders leave the Squadron's universe via their teleporter, but a bug gets in the way of the electronics, and while some of them go home correctly, Namor, Valkyrie, Beast, and Gargoyle reappear in a totally different dimension. This new dimension is a playful parody of the books of Dr. Seuss. Everyone there speaks in rhyme and engages in silliness of the highest sort.
The natives are in a battle between Here and There. Beast, Gargoyle, and Val all think it's pretty entertaining and enjoy their time there, and agree to help the folk of Here, such as Greeneggs and his friend Annham. Namor, however, is not amused, and is in high dudgeon.
Meanwhile Luann Bloom, the 616 Richmond's nurse, wants to investigate Kyle's death, and meets someone who says he can help her. Someone who turns out to be...an Elf! (A character who had appeared in a handful of early Defenders storylines without explanation, years before.)
The Defenders get the folk of There, led by Thornton, who is seemingly a parody of Mr. Rogers, to live happily alongside the people of Here. Their job done, the Defenders are ready to return home, but can only do so via some ruby-red sneakers that only fit Namor. Namor is forced to wear the sneakers and click his heels together and recite an Oz-like rhyme to get them back to their home dimension.