Princess Julia doesn't want to marry an old prince Hubert so she runs away from home. She meets two old magicians and join the circus, where she meets lovely Franta Kuldan and evil devil performer.
In a wooden hut used as a canvassing center, members of a children's puppet-theatre group are rehearsing for a production about a journey to the Moon. The goings-on inside the hut and outside are being closely followed by amateur detective Pepik Barnabás. He, however, is the first to be under suspicion when a trunk containing puppets goes missing. The children follow him but, when they catch up with him, they discover he hasn't got it. Pepík offers to help them in their search.
The series of children's films about Detective Martin, who intervenes in cases involving children, begins with this film. It consists of two short stories: in the first ("Three Bottles"), the young hero, escaping from an orphanage, gets involved in a robbery of postage stamps..., in the second ("Flying Carousel"), the children fight a dishonest owner of fairground rides...
