The Monster of Phineas-n-Ferbenstein

The episode revolves around Phineas Flynn and his step-brother, Ferb Fletcher, being told the story of how their Victorian ancestor helped a scientist create a monster.

In a cold opening with the theme music, Phineas and Ferb warn the audience that the program will be frightening, disturbing, and horrifying.

When the episode officially starts, Phineas is feeling disappointed by the pouring rain and power outage, canceling his plan to stand in the middle of a field with a metal rod, until his step-grandfather Reginald starts to tell the stepbrothers the story of their ancestor, Ferbgor, a hunchback henchman of the Victorian era who assists his master Dr. Phineastein, a mad scientist, in gathering platypus body parts to create a platypus monster and enter him in a "monster ball".

In Reginald's tale, Phineastein and Ferbgor construct and bring their monster to life, which frightens, then angers their castle governess, Constance, and provokes her to rally the mob against them (referencing Candace's attempts to bust her brothers).

In Reginald's story, Phineastein and Ferbgor find the monster and the winner of the ball is announced: it is Constance, who has accidentally drunk Jekyll's formula and transformed into a beast, herself, and gets chased by the mob, presumed to be captured or killed.

[6] Carr and McDowell had each been recurring guest stars in their respective roles;[7] they previously appeared as the characters in "A Hard Days Knight" and "The Flying Fishmonger" and would go on to voice them in season two's "Elementary, My Dear Stacy.

"[12] In 2009, it was announced that "The Monster of Phineas-n-Ferbenstein" was nominated for an Emmy award in the category "Outstanding Special Class – Short-format Animated Programs."

[13] Dan Povenmire and Jeff "Swampy" Marsh, co-creators of the show and producers of the episode, were reportedly "thrilled" about the nomination and felt like they were "back in grade school."