Orion Pax the former Optimus Prime follows a rogue group of Decepticons into one of the greatest mysteries ever to face the Autobots! The mysterious Metrotitan arrives on Cybertron smashing into the ruins of the legendary Crystal City! And, tensions ratchet up between the Autobots and Decepticons as violence breaks out in the heart of the city... and Prowl looks for someone to blame. Is Dirge a convenient target or the key to what comes next?