In an accident, a young dolphin strayed into a crab trap, causing serious injuries to its caudal fin. Luckily, it was discovered by a little boy and went to Clearwater Marine Hospital, where it had a new name-Winter. A whole new life unfolds in front of Winter. For mammals living in the ocean, how important the caudal fin is. Only with the caudal fin can they have the ability to swim, dive and float in the sea and breathe fresh air. Winter, whose caudal fin is damaged, will die of asphyxiation unless he floats on the sea for the rest of his life. To save Winter, a group of highly skilled scientists gathered and used their ingenuity to invent the artificial caudal fin, which became the embodiment of courage and hope.