Aladár converts an old radio into a transceiver, and with the help of this he manages to contact MZ/X, who is none other than Öcsi, the 125-year-old great-grandson of Géza Mézga from the 30th century. While preparing for his high school graduation exam (80 primary and 40 secondary school are compulsory in their country), he stumbles upon his ancestors from the 20th century with the help of the time-dilation device. Géza is in big trouble, his television has broken down, and he seizes this great opportunity and asks Öcsi for help.

Géza goes fishing, but fails to catch a fish. Paula, who has already invited guests for dinner, is overcome by collapse and shame. Help comes from none other than Öcsi, a 30th century relative, who sends superfoods by light mail. The hyperultra extract is extremely tasty and nutritious, with a shelf life of 300 years. But one tablet contains 1 week's worth of food. This may cause some problems.

The Mézga family goes on a camping trip to Baranyaberenye. However, the motorbike cannot fit all the luggage. They get Máris's neighbor's party car as a trailer. Yes, but it also starts to rain. Öcsi needs help here, who sends a weather control device (meteoro-muto-motor) to Géza with authorization from the space authority. However, manipulating the weather comes with serious responsibility and consequences.

The Mézga family is getting ready for a wedding in the countryside, but the car won't start. Who else would Géza turn to than MZ/X, or Öcsi. The new engine from the 30th century, arriving by light post, can do wonders, turning the old, dilapidated car into a real three-wheeled vehicle. They race through the country, on land, in the air and on water, and eventually even manage to run over the wedding party.

Géza Mézga calls a chimney sweep, but Paula protests, and when everything is covered in soot, she packs up and goes home to her mother. Cleaning the apartment falls to Géza, but it is not an easy task. He has to ask Öcsi for help again. However, the settler hyperrobot that arrives by light mail only understands New Hungarian, so he has problems operating it. Géza, insatiable, turns to Öcsi again, and receives an even more modern experimental model in return, the robot director.

A neighbor asks the Mézgás for the French dictionary they borrowed years ago because they are going to Paris for two weeks. Paula scolds her husband because he never takes his family on a trip abroad. Géza now asks for help from his future great-grandson, Öcsi, who offers him a spaceship and interplanetary space travel. Returning home after a tumultuous journey is a joy, but time flies quickly on Earth!

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.

During a visit to a castle, Blöki digs up worn coins from the ground. A neighbor takes over the valuable antique from them, but attributes the price to the family's previous debt. There is no fairy tale, more coins are needed for the desired wealth, but where can they be found? Géza turns to Öcsi, his great-grandson, who uses a time-expanding device to transport the entire family to the 13th century, but one must be careful with the past, and it is good to know history.

The Mézga family goes to the field to pick cherries. However, the harvest is scanty and full of worms, and the vines have not even sprouted. Géza wants to prove to Paula that he is turning their garden into a model farm. To do this, he asks Öcsi for help, who sends a growth-stimulating device from the 30th century, which allows the harvest to be done in two weeks. However, it is forbidden to enter the irradiated area without protective clothing. And if the proper spraying is not done, there may be some problems.

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?

Kriszta sings in the Alfa-Beta-a beat band, which her father doesn't particularly approve of. But in order to make music meaningful, Géza, guided by a newspaper article, takes the entire band to a rural TSZ stable, so that the cows will produce more milk with the music playing. However, the cows and bulls go wild and not only break the stable, but also the instruments, speakers, and amplifier. Needing immediate help, Géza turns to MZ/X, Öcsi, again. However, the sound amplifier device from the 30th century, delivered by light mail, is too powerful.

Géza reveals his secret, so now Paula can also talk to MZ/X, i.e. Öcsi, her 30th century great-grandson. On the occasion of Paula's birthday, she takes the opportunity and eagerly asks for an entire house. Öcsi fulfills his request, and the MAG-LAK selected on the basis of the model is delivered to the lot by the Time Extender Transportation Trans Export Company Association with a space crane the next day. The house is ultra-modern and not for technically backward parents, so there are some problems.