Viktor Taransky (Al Pacino) is working on a movie project. He is running out of money and his star decided not to do it anymore, so his movie is in trouble. A computer programmer named Hank approaches Viktor and tells him that he is able to create a computer-generated character. Hank soon dies of cancer and gives the program to Viktor. Viktor uses the program to insert an actress in place of his original star and the movie is a huge hit. The program, titled "Simulation One," is simplified to "Simone."
Viktor is at first very happy that this is a success, and has her star in more movies. For her voice, he simply speaks into a microphone and the computer makes it a female voice. He conducts interviews. Simone goes on to win an Academy Award and is wildly famous. However, Viktor soon becomes unhappy with Simone and tries to make her unpopular by having her star in a bad movie. However, the people still love Simone and the movie is still a success. Finally, Viktor uses a virus and erases her program from the computer. He then throws a trunk full of CDs into the ocean.
The police come and arrest Viktor and charge her for the murder of Simone. They have a video showing him dragging the trunk into the ocean; they believe that there was a body inside. He tells them that Simone was never real, but they don't believe him. His ex-wife Elaine (Catherine Keener) and his daughter Lainey (Evan Rachel Wood) enter his studio. Lainey ejects the floppy disk, restoring the Simone program, and they create a short movie that shows that Simone is alive and well. The police let him go. Elaine and Lainey convince Viktor that Simone is a symbol now and that they should continue to keep her alive. The last scene shows Viktor and Simone together, with Viktor announcing that Simone and he just had a child.