It seems like the movie could start out with th court room hearing. The government wants the Iron-man specs. Rhodey and Justin Hammer are seen sitting together looking disapointed after Tony refuses.
Rhodey steals the Chrome or constructs his own suit and confronts Tony expressing his disappointment or something. Doesnt go so well fro Rhodey
Rhodey goes to Justin to buy heavy artilary for an upgrade to make War-Machine after Iron-man kicks his ass.
Hammer and Rhodey team up and interrupt Tony and that ceremony or concert thing
During that ceremony it seems thats Ivan Vanko is watching it and thats when he constructs the Whipshlash Mach 1 suit.
Back at the Ceremony after Hammer and Rhodey interrupt Tony and attack him. A chase ensues.
Seems like Tony is able to fight them off and thats when he ends up at the donut shop. Where him and Fury talk. Fury pokes fun at him asking him how the whole solo thing is going.
Later on is where Vanko attack Tony at the race.
It would seem that Iron-man wins this fight and Vanko ends up in some maximum security prison that Tony visits.
Later on is when Hammer recruits Vanko. Asking him to help with the constructing those drones. I know they attacked earlier I would assume Hammer wasn't pleased and wanted to make them stronger. He offers Vanko the tech to construct a Mach 2 version of Whiplash if he helps
Rhodey soon figures out Hammer isn't so good. or perhaps he is persuaded that he was wrong. Possibly by Pepper, Fury, or Natasha Romanoff/Black Widow)
Iron-man and War-Machine team up and take on the drones.
Then later on Iron-man and Whiplash have a final face-off.
Keep in mind this is only my opinion of what will happen. And this is all the major stuff. Obviously it just wont be action action action. I only have to work with what the Trailers have given us. There is obviously a lot more thats going to happen. Especially With Tony and Fury. And in my opinion probably some sort of connection to Thor.