According to the book of the same name by Volodymyr Nikitenko.

It is a story about a brother and sister who try to change the past to save their parents from disaster. To do this, they need to charge the time machine with the energy of good deeds. This amazing machine was invented by the children's father, it works only from the positive energy of good deeds. The children are hindered by the evil Desmond, and by combination - their uncle and guardian, who seeks to take possession of the miracle machine and use it for their own enrichment. On the way back to their parents, children get into various adventures and learn to better understand and appreciate each other more.