The expectant bride Zuzana Vítová accidentally meets in a train to Prague the official Dr. Karel Jánský. After arriving in Prague, it seems that Jánský is watching the girl on the way from the station, but it turns out that they both have only a common path. When Zuzana discovers that her fiance Petr Klika is not at home and that she has lost the keys to his apartment, dr. Jánský gallantly helps her and keeps company until the deep night.