In "Willy McBean and His Magic Machine," the opening frame reveals it is a stormy night and the black sky is suddenly split by a jagged tear of lightning revealing a medieval type castle atop a mountain. In the castle can be seem complicated apparatus bubbling and flashing furiously...the laboratory of Professor Rasputin Von Rotten, a deranged scientist. The professor's obsession is to be recorded as the greatest name in history; he has invented a machine with which he will go back into time and change history, replacing such great names as Columbus, King Arthur and Buffalo Bill with the name Rasputin Von Rotten. As the professor sets feverishly to work the camera moves back into the clouds and there is a dissolve to title----Willy McBean and His Magic Machine---and credits.The storm is still raging. A small town is seen. A monkey comes flying into the picture. He is blown onto a steeple and looks to a long shot of a house. In the house is Willy McBean, a boy of the space and jet age whose hobby is science, electronic devices and invention. He has been sent to his room to study his history lesson, not at all his favorite subject. Willy's attention is caught by a tapping on the window; he opens it to admit the monkey who identifies himself as Pablo. Pablo explains how he had been a prisoner of the mad professor and has escaped. He tells of the professor's intentions to change history and asks Willy to help build a duplicate Time machine from the plans he took during his escape. Willy, not wishing to re-learn all the history he has learned, agrees. The machine built, they go back into Time. Their first stop is Tombstone, Arizona where they meet Buffalo Bill and Sitting Bull, who have come to town to present the famous "Buffalo Bill's Wild West Show. Buffalo Bill and Sitting Bull explain in music-and-song the "new" West --- singing a vaudeville-patter number called "We've Got Show Biz." The professor appears, intent on challenging Buffalo Bill to a gun-down, winning the duel by trickery and earning the name of Rasputin Von Rotten, the fastest gun in the West. But, Willy and Pablo foil his scheme, and the professor, using his Time machine disappears. Willy and Pablo follow to...a dock in Spain. They meet an unemployed sailor named Christopher Columbus,, who tells them of his plan to sail to China, but he lacks money. He bemoans his sad situation in song with "You Gotta Go East to Get West." Willy suggests Queen Isabella for financing. She agrees and they set sail West to discover China and the Indies. The professor, appearing as a Chinese interpreter, plans to be history's greatest discoverer by creating a mutiny and taking over the ship. Willy and Pablo again foil him and he disappears as he is being made to walk the plank. Willy and Pablo use their magic Time machine to follow him to...the time of King Arthur. A host of Knights are happily wining, dining and singing "Knights of the Round Table." King Arthur, a puny little man, is very much worried that he might not be able to pull the sword, Excalibur, from the stone to claim his rightful title to the crown. Merlin sets forth to conjure up some magic for the occasion, in the midst of which Willy and Pablo appear. Merlin believes he has created a Genie. Meanwhile, a mysterious Black Knight shows up. It is Von Rotten who plnas to pull the sword himself and become the greatest King in history by replacing King Arthur. But Willy and Pablo give him another case of the Drats. The professor charts a course for Egypt and our heroes plan to follow but there is a dial misfunction and they finds themselves in a dark, dank dungeon-like cellar with caged animals. They escape it but the exit leads them to to Coliseum facing lions and tigers ready to devour them. Like Harry, they make a hairbreadth escape. Meanwhile, back in Egypt, the professor gets the job of consulting architect to help King Tut construct a monument to last for centuries. The professor has plans to replace the Sphinx with his own face. Willy and Pablo appear and the professor tells Tut they are spies and should be fed to the crocodiles. But, at that moment, the giant monumnet, designed by the professor, whose many skills did not include being an architect, crumbles and collapses. Von Rotten runs to the rubble as the King and Queen unhappily sing "Two Tuts in a Rut." Willya and Pablo explain to them how to stack the rubble to form a new monument. It becomes the first Pyramid. The trail left by Von Rotten is one that leads to the Age of The Cavemen. They find mist rising from the ground of a prehistoric land with wild animals and cave dwellers. The professor, to cement his stature as the world's greatest inventor, plans to come up with the Wheel and Fire. Willy and Pablo, while talking and singing (possibly the world's first song) with the locals, are interrupted by the most terrible monster of all time, the "Big Big." The cavemen throw rocks at it and, then, the professor's Time machine, apparently stranding Von Rotten in the Age of the Cavemen. Pablo, of Spanish descent as his name plainly shows (there was no political-incorrectness in The Age of the Cavemen) defeats "Big Big" toreador fashion, thereby setting the rules for bullfighting, albeit the size of the opponent scaled down over the centuries. Von Rotten repents and promises to reform and hitches a ride back to the 20th Century. There, Willy and Pablo discover the people around them are counterpart look-alikes of the people they encountered while traveling on Willy's Magic Machine. Willy also discovers that Professor Von Rotten has acquired the job of history teacher at his school. The story of "Willy McBean and His Magic Machine" ends on a note of suspicion that Raspution Von Rotten's motives are still suspect.
Output: Question: Who does Willy go back in time to stop?, Answer: Professor Von Rotten