In1903,AmericanseamanHenryAdams(GregoryPeck)isstrandedpennilessinEnglandandgetscaughtupinanunusualwagerbetweentwowealthy,eccentricbrothers,Oliver(RonaldSquire)andRoderickMontpelier(WilfridHyde-White).Theygetabanktoissueaonemillionpoundnote(£1,000,000),whichtheypresenttoAdamsinanenvelope(onlytellinghimthatitcontainssomemoney).Oliverbelievesthatthemereexistenceofthenotewillenablethepossessortoobtainwhateverheneeds,whileRoderickcontendsthatitwouldactuallyhavetobespentforittobeofanyuse.

　　OnceAdamsgetsovertheshockofdiscoveringhowmuchthenoteisworth(andthatitisgenuine),hetriestoreturnittothebrothers,butistoldthattheyhaveleftforamonth.Hethenfindsaletterintheenvelope,explainingthewagerandpromisinghimajobifhecanavoidspendingthenoteforthemonth.

　　Atfirst,everythinggoesasOliverhadpredicted.Adamsismistakenforaneccentricmillionaireandhasnotroublegettingfood,clothes,andahotelsuiteoncredit,justbyshowinghisnote.Thestoryofthenoteisreportedinthenewspapers.Adamsiswelcomedintoexclusivesocialcircles,meetingtheAmericanambassadorandEnglisharistocracy.HebecomesveryfriendlywithPortiaLansdowne(JaneGriffiths),thenieceoftheDuchessofCromarty.

　　Then,fellowAmericanLloydHastings(HartleyPower)askshimtobackabusinessventure.HastingstellsAdamsthathedoesnothavetoputupanymoneyhimself;themereassociationwillallowHastingstoraisethemoneyheneedstostartupagoldminebysellingshares.

　　TroubleariseswhentheDukeofFrognal(A.E.Matthews),whohadbeenunceremoniouslyevictedfromthesuiteAdamsnowoccupies,hidesthenoteasajoke.WhenAdamsisunabletoproducethenote,panicbreaksoutamongsttheshareholdersandAdams'creditors.Fortunately,allisstraightenedoutintheend,andAdamsisabletoreturnthenotetotheMontpelierbrothersattheendofthemonth.