Joss Whedon seemed to use the same formula for this movie that he used in the avengers. The villain captures one avenger. There's a battle between some avengers. There's some arguments between the team until one event brings them together. The captured avenger is back with the team. Stark goes to confront the villain, finds out his plan to destroy the world. The villain calls in his army and the battle begins. Eventually, the avengers assemble for the final battle, and hulk smashes the villain out of the picture. Stark finds a way to finish the job, saves the world. And the avengers go there seperate ways, some pretty extremely far. But they'll come back, because we need them to.