The series tells the adventures of half-brother Phineas Flynn and Ferb Fletcher, the same in which both Phineas’ older sister Candace Flynn and their mother and friends are involved. Premise The show follows the adventures of stepbrothers Phineas Flynn and Ferb Fletcher, who are between eight and ten years old. [2] [3] They live in the fictional city of Danville in an unspecified tri-state area, as they seek ways to occupy their time during their "104 days of summer vacation ".