From the liner notes

Four million years after crash-landing on an unfamiliar planet, sentient robots with the ability to disguise themselves as common vehicles awaken on present-day Earth. Desperate to find a new energy source for their home planet of Cybertron, Optimus Prime and the heroic Autobots must defend their new friends — Spike and Sparkplug — and the innocent people of Earth against their archnemeses, Megatron and the power-hungry Decepticons.