Transformers Prime: Volume 1 - Darkness Rising

It has been three years since the Decepticons last attacked Earth and the Autobots await their return. After the death of Cliffjumper, the Autobots fight to protect the Earth from the Decepticons and befriend three young humans, and the returned Megatron who has been missing for three Earth years. Using Dark Energon, Megatron plans to raise an undead army of Cybertronians and defeat the Autobots. The Autobots destroy his space bridge and Megatron is believed killed in the process. Starscream becomes the new Decepticon leader.