On a scorching summer day, Tom is sitting on the beach, calmly applying sunscreen and lotion to his body. He then digs a sand pit, lies down in it, and covers his head with a towel for a short rest. Just then, the cheerful little mouse Jerry comes walking from afar, carrying a fishing rod. He doesn’t notice Tom lying beneath the sand and casually steps on him, accidentally falling into Tom’s mouth and nearly choking him with the towel. The angry old cat, realizing Jerry has disturbed his nap, follows him to cause trouble. The two rivals engage in another round of back-and-forth fighting, until Tom is struck hard on the head and falls into the sea. Unable to swim, Tom struggles desperately but still sinks to the seabed. There, he suddenly discovers he can breathe underwater—and meets a little mermaid who looks exactly like Jerry…