Bumblebee, an Autobot scout, has been on Earth for ages, covertly hunting for the allspark to signal his fellow Autobots.

A Decepticon interrogation revealed the allspark's map is inscribed on a set of ever-changing glasses created by Megatron, who's also in pursuit.

Mistakenly bought by an eccentric mechanic, Bumblebee, disguised as a car, ends up in a garage, getting cleaned, instead of with the intended glasses' owner.

Bumblebee is trying to stay hidden and not be discovered so he is in car form