Fifteen-year-old Kateřina will once again spend the holidays at the Castle Krabonoš, where her parents are both wardens. She finds it dull because she's got to sit at the castle's ticket office and sell tickets. That is, until the arrival of the new tour guide, Petr, a young history student. She falls in love at first sight. But for Petr she's just a young crazy girl. Katka tries to get Petr's attention in various ways, but all in vain. She makes a last ditch effort by pretending to steal some rare castle steins from the castle's collection. It's only after some detectives arrive that Katka realizes that she may have overdone it, but she finally manages to get Petr to notice her.