At the edge of the town of Green Glade stretched the Emerald Lake. Clouds were reflected in its sparkling surface, and on summer evenings the air smelled of mint and holidays. Olive, Kuba and Lena met every afternoon on the small wooden footbridge to plan new adventures. Olive, the eldest, had a head full of ideas and was never afraid of a challenge. Kuba was the best swimmer in school and Lena was a master at solving puzzles. One evening, during a full moon, Lena noticed something strange. In the middle of the lake, where there was usually only water, there was the small outline of an island. The three friends knew perfectly well that no one had ever sailed there, and the adults claimed that such an island did not exist. - Can you see it? - Lena pointed with her finger. - There is an island! Olive took out her transparent binoculars and put them to her eyes. - Actually... Did she only appear today? - My grandmother used to say that unusual things happen here during the full moon," Kuba muttered. The moment of silence, during which they looked at the mysterious island, was full of tension and excitement. Should they really go there? The next day the boys prepared Kuba's grandfather's old boat. Lena had brought a torch and a small notebook to note down everything they would see. As the sun began to hide behind the trees, the friends carefully got into the boat and started rowing towards the island. With each passing minute, the fog grew thicker and the sound of the water became quieter, as if the whole lake had held its breath. Shadows of the moon danced on the waves, and strange muffled sounds came from the island. Suddenly, just offshore, they noticed something that made all their hair stand on end. Amidst the indistinct contours of the island, a yellow light shimmered, and in its glow the silhouette of someone - or something - that neither of them had ever seen before shone through. The friends looked at each other in suspense. Should they take one more step forward, or would it be better to turn back?