A mermaid Ariel falls in love with a human prince. An unheard of event for underwater royal court and her father - the king of the sea, Triton. At first glance, there is no chance for the couple to be together, but love will overcome all obstacles. But to achieve the goals, one has to pay. Ariel must either forget all her relatives and go to the land in the form of an ordinary girl, or to refuse the call of the heart and stay in the ocean with her loved ones.