Snapped: Killer Couples (2013)

S2E32 Finding Mary McGuffin

In a twist of fate, Dad unintentionally sells Candace's beloved doll during a yard sale. Determined to recover it, Phineas and Ferb step into the roles of detectives, questioning different people in their quest. Meanwhile, Perry the Platypus embarks on his own mission, trying to reclaim the doll from his arch-nemesis.