As you can tell, I'm really pushing the Inhumans Saga for the 3rd movie. I would love to see the Fantastic Four each have someone to fight who can challenge their powers. These pairings are for the initial confrontation. I see it going something like this:
Mr. Fantastic vs Medusa
Invisible Woman vs Karnak
Human Torch vs Gorgon (or Crystal or Triton)
Thing vs Black Blot
Well here are my thoughts on possible storylines...Interestingly enough my story ideas are based on where Attilan is located!! Over the years Attilan has been re-located many times, but where would you like to see this Hidden City for a 3rd movie?
Northern Atlantic Ocean (an island 200 miles southwest of Iceland)
The Himalayas (also known as the Great Refuge
a valley mountain range in China)
Blue Area of the Moon (Kree designed oxygen-bearing section)
Idea 1: Maybe they could start off in the Himalayas.
Feeling their existence is being threatened by the 'outside human world' (after the devastating effects of Silver Surfer's arrival and Galactus' attack on the Earth), the Inhumans (being misled by the evil Maximus) reluctantly send an envoy (Crystal) to infiltrate 'human' life and Earth's greatest superhero team...the Fantastic Four. She embarks on her peoples' mission to start a war with humans, however her feelings for Johnny cause her to doubt her mission. After several tense confrontations, the Inhumans join forces with the Fantastic Four to de-thorn the power hungry Maximus. Once back in power, Black Blot re-locates the Inhumans to the Moon to free them of persecution and pollution.
Idea 2: It would also be cool to maintain them on the Moon.
The Inhumans have created an advance civilization utilizing the technology left behind by their creators...the Kree Empire (this would also keep the film series more 'otherworldly'). Lord Maximus, a corrupt and demented member of the Royal Family, has plans to conquer his people. After his failed attempt to win the heart of Queen Medusa, Maximus erases her memories and banishes her to Earth, a place all Inhumans feel is a filthy backwards wasteland for a lower life form. The Royal Family, discovering Maxiums' sinister plot, head to Earth to find her, ultimately seeking out the help of the Fantastic Four in retaking their hidden city.
A sort of central theme for the Inhumans saga could be that a civilizations greatest threat comes from those who would seek to corrupt it from within.