Lung-chieh introduces the merman as his cousin Lee Jen-yu. Meanwhile, Jen-yu reveals the prophecy he must fulfill. Chiang-chiang gets suspicious.

Lung-chieh’s confidence grows as he learns to swim with his friends' help. Chiang-chiang learns a shocking fact and hatches an ominous scheme.

It’s the day of the swimming competition, and Lung-chieh finally stands up for himself. Meanwhile, Chiang-chiang and his dad have other plans.

Lung-chieh achieves a hard-earned victory, but celebrations descend into chaos as he must save his merman friend from being hunted by humans.

Lung-chieh's troubles are far from over as a surprise betrayal leaves Jen-yu in the hands of the fishermen. An unexpected individual joins the rescue.

Lung-chieh puts everything on the line for Jen-yu in the final showdown between the students and the fishermen.