Once allies, Optimus and Megatron are now enemies in a civil war. To prevent Cybertron from falling into Megatron's hands, Optimus jettisons the planet's heart, the AllSpark, into space, then sets out to find it with Megatron hot on his heels. Optimus is determined to defeat Megatron, bring the AllSpark home, and restore Cybertron to its former glory.