The spring nymph Voděnka is actually a girl from the human race who was taken in as an orphan by three magical aunts – Jezinka, Polednice, and Bludička. The aunts entrusted Voděnka with a magical jug and the task of taking care of all the springs and streams. On his way home, a young potter named Jirka gets lost in the marshes and accidentally breaks the jug. He also meets Voděnka, falls in love with her, and promises to fix what he has done. In order to make a new jug, he must complete the tasks set by Voděnka's aunts and also obtain potter's clay from a secret place in the marshes, which is guarded by the treacherous mud goblin Vodouch. Vodouch has his own designs on Voděnka and, together with the wild girl Rosnatka, sets all kinds of traps for Jirka...