In a wooden hut used as a canvassing center of a childrens puppettheatre group are rehearsing for a production about a journey to the Moon The goingson 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 hasnt got it Pepík offers to help them in their search