User blog comment:AgentP/Phineas and Ferb movie/@comment-1758246-20100126095458

Doofenschmirts mass-produces Evil-Inators in the form of store exit alarms. He manages to distribute them among the city's many stores before Perry gets to his lair. Perry destroys his Evil-Mass-Producer-Inator and defeats him in the process. Little does Perry know that the Evil-Inators have already been put in place, and is turning every citizen who is going shopping evil.

So basically the whole story goes like this...

Candace and Stacy are turned evil upon entering the shopping mall. They, along with hundreds of other shoppers, go around causing some chaos. Phineas and Ferb are then busted and are grounded to their room. Issabella sees this and wants to fix everything. She must go through the city in all its chaos and enter the time machine to stop this event from happening.

Will Issabella be able to go back in time to save Phineas and Ferb? Will Doofenschmirts prevail, turning the whole city of Danville evil. Or will Perry save the city of Danville, keeping it out of the hands of the evil doctor?