Transformers When teenager Sam Witwicky buys his first car, what he doesn't know, is that it's actually an alien robot. This isn't the only alien to arrive on Earth. Optimus Prime and a fellow group of transforming robots have arrived in search of the AllSpark. But, Optimus Prime and his Autobots aren't the only aliens to appear. Megatron and the Decepticons are also searching for the AllSpark, and it would do anything to get it, even if it means destroying the city.