Children unwittingly reopen an ancient battle between Autobots and Decepticons.

Optimus and Jetfire attack the ship, but can't stop the Hydra Cannon being deployed.

Thrust flees into the depths of Cybertron, pursued by Hot Shot and Wheeljack - and, separately, Starscream.

Thinking Unicron is defeated, Galvatron and Optimus Prime resume their battle.