On a far northern island, amid the cool sound of waves and the cries of seagulls, lay the village of Vargheim. It was the beginning of the longest days of the year, when the sun barely hid behind the horizon and Viking children could play almost around the clock. Astrid, the ten-year-old daughter of the blacksmith, looked forward to this time, because she knew what it meant - another trip to the Ghost Beach. Astrid was not alone. She was accompanied by Rurik, her best friend who was passionate about collecting everything the sea threw up, and Solveig, a brave and clever girl who was not afraid to enter even the darkest caves. The three of them were always inventing new games: building fortresses out of shipwrecks, searching for amber and looking out for whales. But on this day, something completely different was waiting for them. Early in the morning, before the rest of the village had even woken up, Astrid laced up her reindeer-skin boots, grabbed her warm coat and, quiet as a ghost, slipped out of the house. Rurik was already waiting by the fence, bouncing impatiently, and Solveig was running from the fjord, carrying a wicker basket for 'treasures'. The path to the Ghost Beach led through the forest, among moss and mighty pines. After an hour's walk, the children reached the edge of a cliff, from which the beach could be seen - covered with black sand and the remains of ships glittering in the sun. Solveig was the first to slide down the path, laughing carelessly. Astrid and Rurik ran after her. All three began to scour the beach, each at their own pace. Suddenly, Astrid heard Rurik calling out: "Come here, quick! I found something!" There was something lying there that they had never seen before. It was a horn. But it was no ordinary horn - it shone in the sunlight with a golden glow, and ancient runes were inscribed on its surface. Astrid gently lifted the horn; it was heavy, and when she held it to her ear, she felt as if she could hear the quiet voice of the sea in it. Solveig ran her finger over the runes. "Do you think this is from the sea god? Or maybe it belonged to someone from long ago?" Rurik ventured first: "Maybe I should blow the horn?" Astrid looked at her friends. In their eyes she saw the same thing - curiosity, courage and a hint of anxiety. Rurik gathered his courage, put the horn to his lips and blew. The sound was deep and loud, like thunder in a storm. Suddenly, the sand on the beach began to vibrate, the waves hit harder, and a shape emerged from behind the mist on the sea - a huge ship like the children had never seen before. On the rough water, slowly, majestically, a huge drakkar with a sail as red as the setting sun glided towards them.... Astrid, Solveig and Rurik froze in place, watching as the ship drew ever closer. What or who has arrived, beckoned by the sound of a golden horn? Will the children have to show more courage than ever before?