Felek the hedgehog lived by a quiet stream. Every morning he combed the spikes with grass and whistled. He liked to collect acorns and listen to the splashing of the water. His friends were Magpie Mika and Frog Dot. They all knew every tree and every stone. One morning Felek found a trunk overgrown with moss. In the trunk was a small, round door with a hole. Someone had imprinted a muddy paw on the door. Mica fluttered her wing and whispered: "Someone lives here!" Dot cmoched and touched the hole with her paw. Felek knocked gently three times, as if into a shell. Nothing happened, only the trunk trembled slightly. Suddenly, a green key slipped out of the moss. It was lying right next to Felk, like a fresh leaf. "I think it fits in this hole," squealed Frog. Felek looked at his friends and took a breath. He put the key in the hole and turned it slowly. Something clicked inside and the door vibrated....