ChristianKempenichistheChiefClerkintheTownCouncilinasmalltownontheriverMoselinGermany.HegoestoColognetoattendafamilybaptism,andafterwardsisluredtosamplethewickeddelightsofthebigcity.Hewakesupthenextmorninginacheaphotelroomwithnomemoryofwhathappened,butthere'sastrangewomanasleepinthebedwithhim.Horrified,heheadshomewithhisguiltysecret.Meanwhilehiswifewentontheriversteamertothenexttown;anItaliantenorhasbeengivinghersinginglessonsandhasamorousintentionstowardsher,andhetakesthesamesteamer.TheystayonittoKoblenzandhavetostaythenight.TherestofthefilmrevolvesaroundKempenichandhiswifeastheyalternatelyshowguiltabouttheirownbehaviourandoutrageastheylearnwhattheirspousemighthavedone.