Leopold Kohák married a rich widow a long time ago and now has nothing to do compared to his energetic wife. He's growing old and troubled by the fact that he betrayed his first love Emča and his beloved river Sázava where he spent his childhood and youth. A visit from an old friend Lebeda brings it all back to him. After a nervous breakdown Leopold secretly visits his home instead of going to the spa. A wandering tramp suggest Leopold should bathe in the magical waters of the Sázava, and slowly his youth returns to him.
