**Chapter 1: Setting Sail for Ahtohallan**

The sun was setting over the horizon as Iduna stood on the deck of the ship, her long golden hair blowing gently in the sea breeze. Beside her, her husband Agnarr gazed out at the endless expanse of water, his eyes filled with a sense of adventure and wonder. Their daughters, Elsa and Anna, played at their feet, laughing and chasing each other as they explored the ship. Iduna smiled, feeling a sense of contentment wash over her. This journey to Ahtohallan, the mystical river of truth, was meant to be a chance for Agnarr to connect with his past and find the answers he sought. As the queen of Arendelle, Iduna had always been supportive of her husband's endeavors, and she was excited to be a part of this journey. Elsa, who was 16 years old, and Anna, who was 14, were bubbling with excitement as they explored the ship. They had always been fascinated by the stories of Ahtohallan, and they couldn't wait to see it for themselves. As the ship sailed further out to sea, the wind picked up, and the waves grew choppier. Iduna's grip on the railing tightened as she felt a sense of unease creeping over her. Agnarr, ever the calm and steady one, placed a reassuring hand on her shoulder. "It's alright, my love," he said, his voice soothing. "The captain knows what he's doing. We'll be fine." But Iduna couldn't shake off the feeling of foreboding. She looked over at their daughters, who were now clinging to the railing, their eyes wide with fear. "Elsa, Anna, come closer to us," she called out, her voice carrying over the wind. As they obeyed, Iduna wrapped her arms around them, holding them close as the ship rode the waves. But despite her best efforts, the storm grew stronger, and the ship was tossed about like a toy. Iduna felt a jolt of terror as the ship lurched violently, throwing her and her family off balance. She heard Agnarr's cry of alarm as he tried to grab hold of something, anything, to steady himself. And then, in an instant, everything went dark. Iduna's world went silent, and she felt herself being pulled under the water. She struggled to swim back to the surface, but it was no use. She was weightless, floating in a sea of nothingness. When she finally came to, she was lying on a sandy beach, her head pounding and her body aching all over. She sat up, groggily taking in her surroundings. The ship was nowhere to be seen, and she was alone. "Agnarr?" she called out, her voice hoarse from shouting. "Elsa? Anna?" But there was no answer. Iduna stumbled to her feet, her eyes scanning the horizon for any sign of her family. But she was alone, and she knew that she had to find help. She took a deep breath and began to walk, her feet carrying her towards an unknown fate. As she walked, Iduna couldn't help but think of her husband, Agnarr, and how he had sacrificed himself to save their daughters. She remembered the way he had looked at her, with a sense of love and devotion, and she knew that she would never forget him. Iduna's heart was heavy with grief, but she knew that she had to keep moving forward. She had to find her daughters and make sure they were safe. She took another step, and another, her feet carrying her towards a new beginning.