Get That Bigfoot Outta My Face, It's a Mud, Mud, Mud, Mud World

Candace and the boys visit their grandparents at a lake house and the boys try to scare her with a fake Bigfoot while Doofenshmirtz goes out on a date and Perry gets ends up in the middle of it.
Phineas and Ferb create a monster truck for Candace to practice driving while Dr. Doofenshmirtz tries to find investors for his line of monster trucks that are actual monsters, with a trump card to take down the competition.