Phineas and Ferb are stepbrothers who spend their summer vacations carrying out ambitious projects despite their sister Candace's attempts to catch them. Some of the main characters are described, including Phineas and Ferb who are very clever and inventive, their sister Candace who tries to catch them, and their pet platypus Perry who leads a secret life as a spy. Dr. Doofenshmirtz is introduced as an evil scientist who often tries to take over the world but also has a soft side as a father.