Optimus Prime returns in "", which is set three years after the events of the previous film. Having been frozen in the vacuum of space, Optimus has been drifting on the far reaches of Earth's solar system for some time. However, he later crash-lands on Cybertron, its atmosphere reviving him. He then confronts the being currently in control of the planet, a powerful sorceress named Quintessa, who professes to be the maker he is searching for. Optimus is easily subdued by Quintessa, who convinces him that he destroyed Cybertron and reveals that the Earth is actually Cybertron's "ancient enemy" Unicron. Redubbing him "Nemesis Prime", Quintessa brain-washes Optimus and tasks him with retrieving her stolen staff, with which she plans to drain Earth/Unicron's life force so that Cybertron can be restored. Nemesis succeeds in retrieving the staff, but is hindered by Bumblebee, whom he engages in a fierce duel. Nemesis nearly kills Bumblebee, but when the normally mute Bumblebee suddenly speaks, urging Prime to remember who he is, the sound of his oldest friend's voice is enough for Optimus to return. However, Megatron, revealed to be in league with Quintessa, swoops in and steals the staff from Optimus. Prime is then attacked and sentenced to death by the Guardian Knights for aiding Quintessa, but he is saved by Cade Yeager, who convinces Optimus to correct his mistake. Optimus leads the Autobots in the attack on Quintessa's lair, during which he slays the Infernocons and defeats Megatron. Optimus then attacks Quintessa, distracting her long enough for Bumblebee to shoot and seemingly vaporize her. At the end of the film, Optimus and the other Autobots return to Cybertron, unaware that Quintessa is actually still alive.