Master Builder is the 5th episode of the Jumanji animated series. It marks the first appearance of Professor Ibsen, soon to be a recurring Jumanji inhabitant, as well as the notion that some of Jumanji's inhabitant wildlife are creations of his design.


At home in the Parrish Mansion, Peter struggles with his homework and wants to use Judy's laptop, but she warns him that if he doesn't solve his own theoretical problems by himself, he never will.

During their next visit to Jumanji with the clue "I can make fish swim! I can make birds fly! I can make you run! But don't ask why!" they are sighted by Van Pelt, who takes a shot at them just as Alan pulls them out of the gun fire range. The trio lose Van Pelt up a steep hilltop as he dislikes the Giant Bees that built a hive on-top. After Alan duels with the Bee drones, they retreat to a cave before reinforcements arrive.

Inside the cave, Peter reveals he borrowed Judy's laptop computer and brought it with him to Jumanji to solve Alan's clue. Judy is initially angry but instead has Alan describe everything he learned in Jumanji over 20 years, to configure a solution.

Sunset approaches and they must escape the cave as Berbalangs come out and attack at night. The Berbalangs start to overwhelm the trio until they are blinded by a set of bright lights coming from the truck of Professor Ibsen who they have never met before but he gives them a lift to his laboratory anyway, where Alan sees mechanical skeletons of some of the dangers he's faced in Jumanji. Ibsen reveals he creates some of the dangers in Jumanji, believing he provides Jumanji's realm a great service by enhancing the fantastic experiences of it's creatures and even sends a daily report to Jumanji itself, which he broadcasts throughout the jungle at precisely 8:00pm.

Judy plugs her laptop computer a large mainframe database which gives her laptop the ability to analyze everything in Jumanji and predict the future, revealing that within seconds a flash flood will hit. Ibsen retreat to shelter but is instantly attracted to the laptop, intending to retrieve it. The trio escapes the flooded lab, but hit a fork in the road and are chased up a tree by Hyenas. Alan feels betrayed that Judy tries to get find the right way and his clue against his own judgement, just as Ibsen knocks the tree down to steal the laptop. He uses it to create even more monstrous creatures, reform damaged ones, and reshape the terrain to make it more dangerous.

The trio race through the jungle, avoiding his creations and fake their deaths by jumping into a whirlpool. Alan comes up with an idea to retire Judy's laptop while Ibsen is busy doing his daily report, as 8:00pm is due. During the report, the trio evade Van Pelt and Purple Flowers, while Ibsen makes a speech about how he now not only rules Jumanji but has become Jumanji itself and Peter figures out their clue. At his lab they try stealing the computer back, but his machines attack, and then the computer overloads creating a Tornado. Peter realizes their clue ties in to how to stop the computer. He asks it "why", which it tries to answer but cannot since it has no context and it shuts down. Ibsen shuts down too, revealing that Ibsen is also a machine. His factory is destroyed and the kids return home.

At home Judy tells Peter to finish his homework before they return to Jumanji and offers him the use of her computer which she'd denied him earlier, but he decides to do it by hand.


  • Ibsen refers to one of his designs being the Acid-Tounge Frogs, which appeared in the following episode.
  • The "Backstage" of Jumanji which appears in the next episode closely resembles the workings of Ibsen's lab, questioning who made it.
  • Ibsen sends out a mechanised Hippopotamus which succeeds in its design until it is sunk by quicksand. In Air Judy, he unveils a new design of mechanised Hippo he refers to as the "Hippopotamus of doom".