Phineas and Ferb: Day of the Living Gelatin!/Elementary, My Dear Stacy

Phineas and Ferb fill Isabella's swimming pool with bouncy gelatin, and it comes to life when Dr. Doofenshmirtz's "Evil-inator" machine is accidentally unleashed. While the kids have a blast battling the gelatin, Candace is stuck floating in it after the creature swallows her whole./ The family takes another trip to England to visit the grandparents and bring Candace's friend, Stacy (Kelly Hu, "X2"). When Phineas and Ferb get caught up in something mysterious, Candace and Stacy use their newfound sleuthing skills to figure out what they are up to. Meanwhile, Perry is teamed with his British counterpart, Agent Double O-O (Damian Lewis, "Life") to stop Dr. Doofenshmirtz from stealing Big Ben.