Kriszta is in trouble with the Mézgás and Aladár has also been kicked out of school. The head of the family again asks Öcsi, who lives in the future, for help. Öcsi sends the brain-enhancing drug, the so-called Brain Resin, but the liquid is accidentally drunk by Blöki and Maffia. Its miraculous effect shocks the family: the dog and the cat start talking. First, they take them to the scientific society, but they don't pay attention to them. Finally, on Mézgá's idea, they take the animals to the circus to make money with them. The idea doesn't work because the two animals get angry and they have to run away from them.