WhenaseriesofapparentlyminortheftsplaguesauniversityhostelryrunbyMissLemon’ssister,Poirotisrecruitedtoinvestigate.CeliaAustin,apharmacologicalmajor,confessesthatsheisakleptomaniacandresponsibleformostofthetheftsbutdeniesstealingseveralobjectsincludingastethoscope,lightbulbs,andastudentrucksack.Furthermore,sheclaimstoknowtheotherthiefandvowstohelpreturnthemissingitems.Unfortunatelysomeonesubstitutesanoverdoseofmorphineforoneofhersleepingpowders,andshetakestheidentityofthethieftothegrave.Jappconnectsthemurderer’sm.o.withacoldcasehehadinvestigatedtenyearsearlier,buttheprimesuspectinthatcrime,apowerfulstatesman,nowliesdyinginalocalhospital.Despitenumerousobstacles,Poirotisabletolinkthekillingtoaninternationaldiamondsmugglingringbutnotbeforethemurdererclaimsmorevictims.