The house under the big lime tree smelled of mint in the evening. Poli and Teo's bathroom had blue tiles like waves and a round mirror in a white frame. On the shelf stood a pea cup, a Tic-Tac hourglass and two toothbrushes: Poli's pink Sparkle and Teo's green Tuptuś. - 'A pea's grain of toothpaste,' reminded Mum, putting a drop of Peppermint Teddy on each hair. - Circles, sweep and tongue. Ready? Pola was seven and liked to hear the toothbrush humming like a quiet rain shower. Teo was five and wore pyjamas with stars. They both turned on the Tik-Tak hourglass. The sand began to fly and they moved the toothbrushes in little circles against their gums, tooth by tooth, front, sides and back. - Wheels, wheels, no speck escapes us,' muttered Teo, and Poli's sparkle shone like a torch, as he had a tiny star on his hand. The foam grew like a cloud. Pola remembered not to swallow. They gulped the foam into the basin, and the fresh taste stayed on their teeth. Then they gently ran it over the tongue to keep it clean. - Bravo, Team Smile! - smiled Mum. - Still a thread. Will you help Teo, Polu? Mum showed them the thread stick Thread. Pola held it securely and Teo looked in the mirror as if he were a dentist. Slowly, carefully, they slid the floss between their teeth, from side to side, in no hurry. - 'Great,' whispered Mum. - 'I'm going to get a towel. Call me when the sand runs out. As she left, the mirror fogged up and Pola drew a smiling tooth on it with her finger. The pair arranged themselves in lines like the paths of a city. The hourglass quietly beeped. Tick... yes... tick... Suddenly, the pea cup chimed as if someone had tapped a silver bell on it. Pola's glitter glowed stronger. Along the frame of the mirror, tiny lights lit up, one by one, like stars above a lime tree. - Can you see it? - Teo lowered his voice. - The mirror is blinking! The sand in the hourglass was coming to an end. Tick... yes... The last grain fell and... something clicked. A tiny tooth-shaped flap slid out at the bottom of the frame. A cool, mint-coloured mist flowed from it, and a warm light shimmered inside. - Hello? - came a whisper, as if from far away. - Is it Pola and Teo? We need clean heroes! Pola and Teo froze next to the washbasin. A crunch came from the flapper, as if someone was crunching sweet crystals behind the door. The flash itself headed towards the crack, and a picture flashed on the light: a small smile with dots. - Can you hear it? - Pola squeezed Teo's hand. - 'There's someone in there. The mint mist grew thicker, the lights on the frame flashed like fireworks, and the flap began to slowly widen, revealing what looked like an alley made of white cubes....