In the 1930s, the beggar sea cat returned to Haiyang, Shandong to find relatives. Unexpectedly, the Wu and Zhao families of Hutou Bay, who have been feuding for generations, not only forced the sea cat's father and mother to death for violating clan rules, but also drowned the sea cat in the sea. Miss Wu Ruoyun of the Wu family, fisherman Zhao Xiangyue, and the pirate Black Shark teamed up to rescue him. The sea cat who survived the disaster made a big fuss in Hutou Bay, but was framed again by the heads of the two families. Hai Mao was unjustly imprisoned and sentenced to death. Fortunately, he met Wang Tiankai, a member of the underground party, and used a trick to regain his life and change his name to Hai Long. It was Hai Long, the "monster" in the eyes of the people of Hutou Bay, who not only saved his homeland from the Japanese invaders again and again, but also used the Yangko fight as an opportunity to bridge the centuries-old grudges between the Wu and Zhao families. Under the leadership of Hai Long, the people of Hutou Bay finally eliminated the "Eight Immortals Group" of the military spy organization and truly became the masters. An abandoned child, filled with the deepest love and hatred in his heart, wrote a passionate legend on the land of his hometown.