On the edge of the town of Zgryziołów there was an old house that was said to hide a secret tunnel underneath. One summer afternoon, Lena, Oskar and their younger brother Filip decided to take a trip there. Armed with torches and sandwiches, the three friends descended the creaking stairs to the cellar. The cellar smelled of dust and something minty. Oskar found a trapdoor behind a bookcase, under which a stone staircase was hidden. As they descended them, they felt the air growing fresher and strangely minty. Philip squeezed his toothbrush tightly, which he always carried with him because he didn't like anything left between his teeth. At the end of the stairs, the children found themselves in a huge cave, full of coloured lights. Glistening stalactites resembling toothbrushes dangled from the ceiling, and snow-white crystals glimmered in the walls. Suddenly, a little creature ran out from behind one of the crystals - he had a body like a piece of toothpaste and a funny green cap on his head. He introduced himself as Captain Mint, Keeper of Clean Smiles. He told the children that strange things had been happening in Toothport for some time - the crystal teeth had started to darken, and the cave dwellers, such as Toothbrush, Floss and Rinse Water, were very concerned. Lena looked around and noticed footprints on the ground.... They were the footprints of a giant, fuzzy paw, as if someone was carrying a huge lump of sugar! Captain Mint asked the children to help discover where the threat was coming from and how to save Tooth Harbor before something really bad happened. At the same moment, a rumbling sound sounded and the tunnel the children had come through began to slowly close. Oskar gripped the torch tighter and Philip pulled out his toothbrush like a sword. A giant figure appeared in front of them and slowly emerged from the shadows....