Mickey's car malfunctions during a storm and he doesn't want to lose the boxing match. Luckily, he's close to Goofy's house and goes to ask him if he can drive him to the match. But before, Goofy shows him his new invention: an strange calculator machine. When Goofy crosses the wrong cables, the machine becomes a little robot named "Charlie" by Goofy. However, Charlie cannot answer even the basic math problems. Mickey reminds Goofy the wrestling match and when they are about to go, Goofy convinces Mickey to bring Charlie with them, as the robot looks sad.
At the match, Charlie produces a paper with the result, and the victor is the one said by the paper. Later, Mickey decides to do another test, the result of a rugby match, and Charlie guesses right again. Mickey notices somebody spying them, so he decides to go after Inspector Casey. In the meantime, Goofy watches a mystery movie, but Charlie spoils him the ending.
The spying guy, Little Echo, uses a magnet to catch Charlie while Goofy isn't looking, but Charlie manages to leave a paper predicting where will he be taken, so Casey and Mickey find it when they arrive.
Little Echo brings Charlie to his boss, the Great Elmer, who wants to use him for his fortune-teller business. Charlie gives accurate predictions, but writes them in a way that when Elmer reads them to the clients, they feel offended and hit him. When Mickey and the others arrive, Elmer escapes, but Charlie leaves another note.
Elmer and Little Echo hide in a barn where they have hidden weapons and food, but Charlie predicts they will be caught. This angers Elmer, who throws Charlie through a window. The cops arrive and Elmer denies knowing Charlie until Goofy finds the badly hurt Charlie. While Casey handcuffs Elmer, Goofy tests if Charlie still works by asking him who will be the next president. Then Charlie reveals he has lost the prediction power, but instead has become able to solve the math problems he was first built to solve.
Mickey and Goofy open a small store and use Charlie as their calculator machine, which the customers find cute and funny.
- The story implies Mickey already knows Inspector Casey, but he looks nothing like his better known namesake Detective Casey.
- A sequel story was made in Brazil, with the title "A Volta de Carlinhos".