The legend of the Black Sea tells the story of an old man who lives quietly weaving nets by the shore of a beautiful sea. He shares his catch with his obedient dog Boley and mischievous black cat Serzhina. When the old man falls ill, Serzhina refuses to fetch his medicine until promised a fish, while Boley helps the man without hesitation. A herring gull later tells the starving man to cast his net and it becomes full of fish again. However, troubles soon follow as the sea turns black and fishing fails until a hungry black kitten appears in need of help.