The boys learn about one of Ferb's Victorian ancestors, who helped a scientist create a monster. Meanwhile, Doofenshmirtz recalls the story of his great-great-grandfather Dr. Jekyll Doofenshmirtz.
Quest roles:
Jane Carr(Grandma Winnie (voice)), Malcolm McDowell(Grandpa Reg (voice)), Jennifer Grey(Additional Voices (voice)), Jeff Bennett(Additional Voices (voice)), Candi Milo(Additional Voices (voice))