Following the events of the finale of the first season, Optimus, as Orion, is converted into a Decepticon when Megatron takes advantage of his amnesia. Jack goes on a mission to help the Autobots restore Optimus' memory and they eventually succeed. With his memory restored, Optimus regains the power of the Matrix as well as his leadership of the Autobots. The main theme for the rest of the season is the discovery of ancient relics from Cybertron buried on Earth with the Transformers fighting over each new discovery which ultimately leads their battle all the way back to Cybertron. New characters introduced in the second season include a young Autobot named Smokescreen, Optimus' old mentor, the archivist known as Alpha Trion, Optimus' evil twin, Nemesis Prime, and the Decepticons known as Shockwave and Dreadwing as well as a swarm of Insecticons.