Since there will be two more live-action TF after this summer's blockbuster, this is how I believe that the general story will be covered. Movie #1 - Intro to world of TFs. TFs bring their war to Earth and are first introduced humans. Mass audience is introduced to world of TFs. Movie #2 - War shifts back to Cybertron, Witwicky goes there as well. First human to set foot on Cybertron. Introduces Cybertron to mass audience. Many new characters are introduced as well as 'Seeker-style' repaint characters. Film delves much further into TF mythos. Movie #3 - Intro to Unicron, Earth is destroyed, only a few humans along with Witwicky survive. Story becomes much more focused on TFs and interactions between themselves. Witwicky wants to fight but is forced to be isolated with other humans to ensure their survival. Prime wouldn't want to be responsible for wiping out an entire race. Alliances are formed and alliances are broken as the war against Unicron begins. Film ends with a conclusive ending, but leaves room open for further seqeuls. Third film appeals much more to hardcore fans than previous two, done so because casual fans would be up to speed by that point.