I've got an idea which I've been floating about for the last 2 years, I even went so far to start writing it as a book but haven't touched it in a while (got about 1/4 there) & I've got a premise. Basically set in the future in a Solar System with many planets & 6 races all similar in look but have certain unique attributes, & its set in the 2nd Solar (System) War.
Its about the main character, Matt Dark, who was a soldier who worked for the United Federation but realized after witnessing & doing certain things then started to leak out infomation & military plans to the other side, they eventually found out & the Confederate Alliance offered him sanctuary but when the pick up ship arrived he was ambushed & in the midst of fire lost his wife & young child. Then it fast forwards 4 or 5 years & he's retired on one of the Confederate's planets, he gets a call & is asked to lead a small group of double agents (meaning all are from races belonging to the United Federation making them perfect for blending in) & will be given certain targets they have to assassinate which will not win the war but weaken the opposing side. The catch is it will be a "Seasons Mission" meaning it will take multiple seasons to complete & they will have no support, they will be sneaked onto a planet & they will have to acquire any equipment & contacts on their own & if after a year or so the targets aren't eliminated the Confederate Alliance knows they have failed or died.
So its not some film about a hero really just a man doing what is right trying to forget the bad stuff he has done, he doesn't have much will to live so he accepts the mission (possibly hoping to die), its not about saving the worlds just a slightly important assassination(s) mission, its not a revenge movie though does play on his emotions, & there is no big bad guy.
If you want to hear more I can send you any information I can dig up, bare in mind my half arsed book is very rough & doesn't have finalized names, also my premise differs slightly to my book since I revise the story every now & then + I even have a second concept of the same sorta story lying around. But you could change anything you want