While desperately searching for his missing daughter, Hae-kwan comes across an AI satellite robot that remembers sounds from all over the world. Rejuvenated by the robot's abilities, Hae-kwan begins to track down his daughter's voice. As they continue their journey, they form an unforgettable bond.

Based on the true nail-biting mission that captivated the world. An international team of elite divers is mobilized to rescue a boys soccer team trapped in a cave by rising floodwaters.