It is late evening in Tosi's bright bathroom. A little girl in soft pyjamas stands on a stool. A toothbrush with a blue handle waits in a cup. The toothpaste smells of strawberries, like a summer dessert. The clock-fish ticks evenly for two minutes. Tosia remembers: a small dot of paste, no more. Gentle circles over the teeth, front and back. At the end, the tongue gets a wash too. Suddenly the mirror slightly foggy flashes a silver speck. Behind the cup, a tiny tooth-shaped door opens. Out of them comes Miss Frotka, tiny as a thumb. "Hello, Tosia! Your clean help is needed!" In the City of Teeth, sticky Sludges grow. They obscure smiles and push themselves into crevices. Only a good toothbrush can chase them away. Tosia wets the bristles until they shine like a torch. Miss Frisky blows and Tosia suddenly shrinks. They jump through the door straight under the sink. There is a square with milk houses and a tap fountain. The wash bells are ringing, everyone is hiding sweets in boxes. Suddenly a pipe hisses and it gets darker. From the drain comes a shadow in stripes of icing. It smells sweet, but the air sticks like tape. "It's the Sugar Vortex!" shouts Frotka and points to the bridge. "If it floods us, the town will lose its smile!" Tosia lifts her toothbrush and takes the first step.... Something huge is bubbling just beyond the bridge.