The plot: The boy finds a fish on the ground and lets it go back in the water. Then the fish turns into a mermaid and starts playing around with the boy. He goes back home and puts the mermaid in the water tank. However, his parents says that it is not a mermaid, but just a tiny fish. Then he gets caught by the government which claims that he is seeing something that he should not be seeing. They make him sit on electric chair and try to "cure" him but he still cannot forget about the mermaid. The government does not give up, making him read all the books until he changes his mind. It looked like he finally forgot about the mermaid.
Ending: At the very end, he goes to the place where he first met the mermaid and finds a fish again. He walks into the ocean with the fish. The government people watches them turn into mermaids from the cliff.
Message: I think the message is that we all have the freedom of thoughts and ideas and the government should never take away the rights from people. When the right is taken away, there will not be any creative thoughts and new ideas in the society.