While their mother is out shopping, the boy build a roller coaster. Dr. Doofenshmirtz and Perry battle due to the doctor's evil plan of throwing the earth off its rotation.

Phineas and Ferb decide to become a one hit wonder, Phineas and the Ferb-Tones and Candace wins the chance to sing with them. Meanwhile, Perry must stop Doofinshmirtz's giant robot - disguised as a temp.