Candace's imagination has created Phineas and Ferb. Candace constructs a world in her brain where Phineas and Ferb play together and create beautiful things after being unable to cope with Phineas' traumatic childhood death and Ferb's condition that prevents him from talking or moving much. This imaginary world is called "Inside Out" because it is located inside Candace's mind. Phineas and Ferb are based on characters from Disney movies. The main characters of the show are a brother and sister duo who live in the fictional town of Doofenshmirtz Evil Inc. They use their genius-level intelligence and their father's invention, the Hyperdrive, to fight evil. The series also features other characters who help them fight crime and develop their relationships. Phineas and Ferb first appeared in the 1999 Disney movie titled Phineas and Ferb: Across the 2nd Dimension. The film was written by Dan Povenmire and Jeff "Swampy" Marsh and directed by David Nutter. The plot focuses on two siblings who travel through time using their father's invention, the hyperdrive. They go back in time to change some historical events that are dangerous for humanity, such as avoiding the creation of Hitler. After the success of the movie, Povenmire wrote a script for a new Phineas and Ferb television series.