Maks loved brushing his teeth in the evening – not because he liked the minty taste of the toothpaste, but because that was when he thought most about adventures. It was when he was standing in the bathroom with his sister Lena that something completely unusual happened. ‘Hey, Lena, look!’ Maks pointed at the sink drain. ‘Do you see those strange, shimmering lights?’ Lena came closer and knelt down on the cold tiles. Indeed – there was a thin, coloured mist coming from under the washbasin, which smelled like strawberry toothpaste. ‘That’s definitely some kind of prediction,’ Lena said, although she wasn’t so sure about that herself any more. Suddenly the mist began to swirl and formed itself into a miniature door. On the door was a golden inscription: ‘Welcome to the Tooth City. Come in, for time is running out!’ Maks and Lena looked at each other with wide-open eyes. Then a tiny little creature with a smile so white it was blatant jumped out of the door. He was wearing a cape shaped like a toothbrush and introduced himself: ‘I am Brushy – the guardian of oral hygiene! I urgently need your help!’ Brushy told them that mysterious black holes had appeared in the Tooth City, eating away at the good mood and freshness of smiles. Only children who know the secrets of clean teeth can save the town. ‘Do you dare to enter through the portal and take up the challenge?’ asked Brushy, looking at them with sparkling eyes. Maks felt a slight tingling in his fingers; Lena felt a shiver down her spine. At the same moment, a strange, quiet noise came from the bathroom, and the colourful mist thickened again, inviting them inside. Without a word, they approached the magic door, and a sound rang out just behind them… And just then…