ThesettingisViennain1914beforetheoutbreakofwar.ThearistocraticandsomewhatjadedPrinceNicki,pursuedbyalltheladies,beginsaflirtationwithMitzi,acrippledharpistwhoworksinasuburbanwine-garden,andwhoisinturnidolizedbySchani,anuncouthandviolentlyjealousbutcher.TheirfirstencountersignificantlytakesplaceinfrontofSt.Stephen'sCathedralonCorpusChristiday,withNickiamongtheemperor'scavalryregiment.Later,intherefractedlightoffallingappleblossomsinthewine-garden--scenesofadistilled,etherealbeauty--Nickigraduallywinsherfaithandlove.Meanwhile,amidstthesumptuousandcorruptmilieuofthefamilypalace,Nickiisdrawnintocomplicityagainsthiswill,ashisunscrupulousmotherinformshimhemustmarryCecelia,thedaughterofawealthycommoner,inordertorevivethefamilyfortune.MitzihasavisionofTheIronMan(asymbolofthedecliningpowerandpositionoftheHapsburgdynasty)andfallsbeforethecrucifixinfear;butherloveremainssteadfast,andsheprotestsherfaiththoughabusedbyhermotherandSchani.Infuriatedbyherrejection,SchanithreatenstokillNickionhisweddingdayunlessMitziagreestomarryhim.Followingtheprocessionalsplendorofthecathedralwedding,Schaniappearstocarryouthisthreat,butMitziarrivesintimetostophim;andthroughthedownpouringrainNickisadlygazesonhistrueloveinthecrowdashedrivesawaywithhisbrideddd