One day a Cossack was standing on the shore, staring into the water, trying to catch a mermaid. But she took his imprint, which went with part of the boy's soul. The mermaid fell in love with this imprint and did not want to release it back to land. What should the Cossack do? And how will the mermaid fight the evil and harmful monster that lives at the bottom and tries to lure her to him?