Series Description: Best friends and stepbrothers Phineas and Ferb are determined to make each mind-numbing rotation of Earth into something special. But their sister, Candace, is determined to reveal their crazy endeavors to their mom. Meanwhile, Perry the Platypus-Agent P-is called on repeatedly to save the world from the dangerous Dr. Doofenshmirtz. Spend some time with Phineas and Ferb and see just how exciting and outrageous a summer's day can really be! Chapter Book #6: Daredevil Days When Phineas and Ferb find out that their Grandma Betty Jo used to be a roller derby queen, they build an awesome rink-right in their backyard! Soon they discover that Jeremy Johnson's grandma also used to be a skating champ, and they set up a contest to see which granny can roller derby their way to the finish line the fastest. But Candace doesn't like this idea one bit. After all, she has a huge crush on Jeremy and worries that her grandma will outskate his! The thrills continue when Phineas and Ferb build a gorge so their Grandpa Fletcher can do an awesome stunt jump over it!