With OPTIMUS PRIME stranded on an alternate CYBERTRON, facing the ultimate destroyer of worlds, the Earthbound AUTOBOTS and MINI-CONS launch a desperate rescue bid, spearheaded by OVER-RUN, a MINI-CON from a dimension consumed by the same evil force. On ARMADA CYBERTRON, an advance guard of heralds prepares for the arrival of their dark master, unaware that on Earth, MEGATRON has used the power of the STAR SABER to kill one of their number...