Star Wars Episode III: Revenge of the Sith
Palpatine reveals to Anakin that he is a Sith (evil Jedi). Anakin finds out that Palpatine is in fact the true leader of the Separatists and has been using the war to get more power. Anakin tells Mace Windu, who goes to arrest Palpatine. However, Palpatine uses his Sith powers to kill Windu. Palpatine promises to help Anakin save Padmé from death. Anakin agrees to join the Sith and is renamed Darth Vader.