Olek loved visiting his grandmother, especially when the sun was shining and the garden smelled of colourful flowers. That day, while playing hide and seek with Puffy the cat, Olek suddenly saw something unusual under an old lilac bush. It was a large, purple hat with yellow stars! The boy carefully approached, picked up the hat and put it on his head. Suddenly, things began to happen in the garden that he had never seen before. Butterflies danced in the air and the grass seemed to whisper: "Follow us!" The cat, Puff, made big eyes and started meowing melodiously, as if singing a magic song. Olek felt his hat tremble slightly. A piece of paper with coloured letters on it slid out of his trouser pocket: "If you want to know the secret of the hat, find the door hidden in the garden!" Olek looked around carefully. Is there really a secret door here? Where do they lead? Olek and Puff moved towards the big old tree under which....