Nathan Ham died in an accident, but his sister-in-law wanted to sell his children Luna and Amelia to human traffickers. In order to avoid the traffickers, the two sisters set out to find their mom Josiah Zweig. By mistake, they fell into the trap of the traffickers and were locked up on a boat to Sunking City. At the same time, Josiah Zweig also boarded the same boat, but they didn’t recognize each other. How can the two young sisters persist in their journey to find their mom?