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With my stimulated brain, I am dreaming up all sorts of super smart projects.

— Baljeet

When Baljeet becomes concerned that he is losing his mental edge, his friends invent a cerebral stimulatory hat to help him. But when the hat exceeds expectations and makes Baljeet exponentially smarter, he suddenly views everyone else as beneath him and becomes a threat to civilization by taking Earth's atmosphere and bringing it to the moon. Meanwhile, Dr. Doofenshmirtz plans to use his "Key-Find-Inator" to collect all the keys in Danville in hopes that it will lead to the Key to the City.

Episode Summary

Candace watches the kids playing cards. Baljeet comes in, and Buford brings up the question of who invented playing cards. Baljeet claims that ancient Babylonians created playing cards, but Ferb corrects him and explains that playing cards were introduced in India. Baljeet then realizes that he was wrong, and concludes that, due to the three months of summer vacation, he is losing his edge.

At the antique shop, Lawrence is showing a customer around, and shows her a wardrobe that Perry is sitting near. After they walk away, Perry walks into his lair. Major Monogram informs Perry that keys across the Tri-State Area are disappearing.

In the backyard, Baljeet comes back with two CAT Scans of his brain, one before summer and one during summer. Isabella points out that they look the same, and Baljeet thinks he is slipping because he took three minutes to remember how to give himself a CAT Scan. Phineas then shows Baljeet what they made while he was gone; a helmet that stimulates his brain. The helmet works, as Baljeet performs complex equations.

Perry arrives at Doofenshmirtz Evil Incorporated, where Doofenshmirtz traps him in a water soluble capsule. He then reveals his plan to steal all of the keys in the city with his Key-Find-inator in hopes of finding the Key to the City, believing it will allow him to go anywhere in the city.

Back at Phineas and Ferb's house, Baljeet is testing the helmet. He reveals his new intelligence has given him a lot of ideas, with his favorite being taking the Earth's atmosphere and placing it on the moon, so that everyone would have a better view out of a telescope. His friends try to talk him out of it, unsuccesfully. Buford tries to shut off the helmet's power source, only to be stopped by a force field.

Fooling Baljeet with cardboard effigies, Phineas, Ferb, Buford, and Isabella make their way under the backyard to get to the atmospheric device. Using jet-packs, they distract Baljeet by flying around the device. Thinking he has stopped them with his tractor beam, Baljeet commences the atmospheric transfer process. Candace walks out, notices the device, and calls Mom, who is stuck at the post office because she can't find her keys.

As the weather grows erratic, the Key to the City ceremony begins. Just as Roger hands the key to its recipient, the Key-Find-inator zaps it. Due to the rain, Perry is able to escape from the capsule and attack Doofenshmirtz.

Baljeet continues the transfer, as Phineas warns him to surrender. As he realizes that he was fooled, Buford comes and takes the brain booster off of Baljeet's head, and he returns to normal. Realizing his mistake, Baljeet explains that he can't stop the transfer, as he does not remember the controls. He remembers that there is a failsafe, but he can't find the keys to shut it off.

The Key to the City arrives at Doofenshmirtz's inator. Perry reverses the effect of the inator, sending all of the keys back and causing it to self-destruct. Despite the inator being destroyed, Doofenshmirtz still has the Key to the City. As Perry leaves, Doofenshmirtz is zapped by lightning.

As Baljeet is running around trying to find the key before the transfer is complete, it lands on the key hook. One second before the transfer is complete, Baljeet turns the key and stops the process, saving the Earth. Buford then uses the helmet to create a wedgie machine. As Candace brings Mom into the backyard, the wedgie machine pulls the atmospheric device into space along with the helmet.


Read the transcript of Cranius Maximus.


End Credits

Second verse of "Big Brain".


Click here to view more images from "Cranius Maximus".
View the image gallery for "Cranius Maximus".

Running Gags

The "Too Young" Line

Buford: I think brain boy had enough stimulation for one day. Ow! Hey, that hurts.
Baljeet: Yes, yes, it does.
Isabella: We should do something about that helmet, huh.
Buford: No. No you should not; I used my vastly superior intellect to build the world's largest wedgie machine.

Ferb's Line

Ferb: Actually the Babylonians had been defunct as a distinct culture for millennium prior to the introduction of playing cards in India.
Ferb: It pays to show up on time.

What'cha doin'?


Oh, there you are, Perry

Phineas: Oh, there you are, Perry.

(Perry chatters)

Candace: I'm going to get an alarm clock.

Perry's entrance to his lair

Through a wardrobe in the Antique Shop with everything frozen.

I know what we're gonna do today/Hey, where's Perry?

Phineas: Gang, I know what we're gonna do today!

Buford: And Perry?

Phineas: Who knows?

Memorable Quotes

Baljeet: Clever, but not clever enough.
Isabella: I was so looking forward to junior high.
Buford: No you should not, I created the world's largest wedgie machine.

Baljeet: Uh, you tried to eliminate the atmosphere, one time.

Buford: Ha, ha, ha, ha, ha!

Background Information


Production Information

International Premieres

  • June 22, 2012 (Family Channel)
  • July 19, 2012 (Disney XD Germany)
  • July 21, 2012 (Unitel Bolivia)
  • August 10, 2012 (Disney Channel Latin America and Brazil)
  • November 4, 2012 (Disney XD Spain)
  • December 30, 2012 (Disney XD Latin America)
  • January 7, 2013 (Disney Channel Portugal)
  • January 17, 2013 (Disney XD Poland)
  • March 2, 2013 (Disney Channel Asia)


  • Playing cards originated in China, not India, so Ferb and Baljeet are both wrong.
  • When Doofenshmirtz catches Perry, his shirt starts out white, but when he is putting his pants on, it turns black.
  • Baljeet's pocket disappears and reappears throughout the episode.
  • In the scene where Baljeet sees the decoy models of the gang, Ferb is shown before Isabella, but when the camera jumps to the backyard it's the opposite, and their gestures are different.
  • When Baljeet is trying to stop the gang, a lever is out of place.
  • When the song begins, at one point Isabella's right bangs are the same color as the sky.
  • In the last shot, Candace's eyes flicker from black to blue and vice versa.



  • Circus Maximus - The episode's title is a reference to Circus Maximus, an ancient Roman chariot racing stadium and mass entertainment venue.
  • The Lion, the Witch, and the Wardrobe - Perry's lair entrance is similar to Lucy entering the wardrobe into Narnia. Lawrence alludes to this by joking about there being magical creatures on the other side of the wardrobe.



designates a character that did not appear in this episode
"The Mom Attractor"
Episodes Next:
"Agent Doof"
Phineas and Ferb