Open in the Future, with a tight shot on Captain America's Shield, pull back to see the Original Guardians of the Galaxy fighting a slew of unknown enemies (later to be revealed as the Universal Church of Truth). The Guardians are holding them off to allow Yondu the time to escape through a time portal to the past to prevent the rise of the Magus, with a device that will allow him to track the Magus' power signal in the past.
Cut to Earth and launch of a NASA spaceship that is taking Peter Quill an Astronaut into outer space (pick a reason why), something goes wrong, wormhole or some such, and zip-pow, he's on the other side of the universe... come out the worm hole into the middle of a giant space battle around what appears to be a giant head floating in space.
Cut to Sanctuary (Thanos' Ship for the uninitiated), with the loss of the chitauri army to the Avengers, Thanos enlists the Controller to create a new slave army.
Cut to Knowhere (the afore mentioned giant floating head) Peter Quill is on board, in a bar trying to figure out what the hell is going on, when a disheveled Yondu approaches Peter Quill for help (with an Obvious sense that he know's who Peter is), some hijinks ensues (with a quant encounter with a telepathic Russian Dog) and we have ourselves a rag-tag band of heroes ready to go out and help the time traveler save his timeline.
Quick cut to our first look at the collector talking to his "Aide" (who we all really know is his daughter Carina). He has is first vision of an upcoming war against Thanos.
We're back as our Heroes head out, with the aid of Yondu's device, to track down the Magus. They come to a world that is populated by Bug-like creature that are currently fighting a war against the Contollers forces (a red skinned people...see what I did there, we're on Sakaar total setup for Planet Hulk happening right here... and that same worm hole Quill went through, a reason they have the technology to control other creatures, even a Hulk... I love when a plan comes together. Anyway I digress) Fighting along side the Insectoids is Adam Warlock. Yondu's tracker takes them right into the fight, first they fight off the controllers forces, then we get Warlock vs. The Guardians... It all gets resolved with Yondu pissed and wanting Warlock dead, to save his future, Quill wont have anything to do with it because Warlock's a hero now and cannot be judged for crimes he has yet to commit, they form an uneasy alliance to take on the Controller together. The Insectoids dub Peter Quill "StarLord"
We'll speed this up now, fight through the Controller's forces, epic showdown against the controller, maybe Drax get's controlled and now we get Drax vs. Guardians w/ Warlock (because honestly Drax vs. Warlock in the Soul Gem was pretty awesome, and that was dumb Drax, let's see this with smart Drax!) Good Guys win the day, Drax is saved, Controller is defeated. Thanos teleports in to retried the Contoller's technology (maybe we make it the Cosmic Control Rod, just for giggles to setup an Annihillation movie?) We get a great stare-down shot of Star-Lord, Warlock and Thanos. Thanos teleports out, to Sanctuary and is off.
The Guardians with Warlock all head back to Knowhere.
Back to the Collector, Carina offers to chase after Thanos only to be told by the Collector that there is another matter that requires her attention.
Back in the bar on Knowhere; Quill is talking to Yondu, and Yondu is still pissed that Warlock is alive, Quill promises to keep any eye on him and not let things get out of controll. Yondu takes him at his word, and time-travels back to his own time, only to find that nothing has changed, as we pan across the future carnage, we come to rest on a giant statue of StarLord (similar to the one at the end of the Thanos Imperative)
Roll Credits...
Post Credit Scene
A panning shot of deep space, pull out on huge space ship... it explodes violently... A Glowing naked body flies out through the blast wave across the screen... First look at Michael Korvac
Now, I know this is high-level and there would obviously be great quippy one-liners from Rocket Raccoon, a fair amount of "I am Groot" followed by awesome carnage, Gamora and Drax laying waste in amazing fight scenes, I would also have the Nova Corps be most of the security force on Knowhere, I wouldn't introduce any specific Nova's yet, but in a nut shell that would be the movie I would make, Followed by Guardians 2 with Korvac and Guardians 3: Annihilation... Enjoy!