Transformers Prime - retribution
32 parts Complete Mature(happening after Operation Bumblebee: Part 2) (This is book 1st out of Multiple other books) Team Prime and their human companions are at base and got a Cybertronian energy signature. But it isn't like any other, it is older than Optimus, Ratchet and Megatron, and when they find it, boy they are in for a shock