Aladár is experimenting with a mini solar power plant with the newspaper of the day, and because he earns his father's wrath, he is put under house arrest. This is the perfect opportunity for Aladár to turn to Öcsi. The LUXNIX tablet from the 30th century comes in handy. It makes him invisible for an hour, so he can sneak out of the apartment without being noticed, taking advantage of all the advantages of invisibility in the square and in the amusement park. Aladár is nowhere to be found, the parents are completely devastated! Finally, Géza also asks Öcsi for help, and the secret of the tablet is revealed. But how will they find Aladár?