HauntedbythememoryofWalterHolderlin,asoldierhekilledduringWorldWarI,FrenchmusicianPaulRenard(PhillipsHolmes)confessestoapriest(FrankSheridan),whograntshimabsolution.Usingtheaddressonaletterhefoundonthedeadman'sbody,PaulthentravelstoGermanytofindhisfamily.
Asanti-FrenchsentimentcontinuestopermeateGermany,Dr.Holderlin(LionelBarrymore)initiallyrefusestowelcomePaulintohishome,butchangeshismindwhenhisson'sfiancéeElsaidentifieshimasthemanwhohasbeenleavingflowersonWalter'sgrave.Ratherthanrevealtherealconnectionbetweenthem,PaultellstheHolderlinfamilyhewasafriendoftheirson,whoattendedthesamemusicalconservatoryhedid.
Althoughthehostiletownspeopleandlocalgossipsdisapprove,theHolderlinsbefriendPaul,whofindshimselffallinginlovewithElsa(NancyCarroll).WhensheshowsPaulherformerfiancé'sbedroom,hebecomesdistraughtandtellsherthetruth.SheconvinceshimnottoconfesstoWalter'sparents,whohaveembracedhimastheirsecondson,andPaulagreestoforegoeasinghisconscienceandstayswithhisadoptedfamily.Dr.HolderlinpresentsWalter'sviolintoPaul,whoplaysitwhileElsaaccompanieshimonthepiano.
Thefilm'soriginaltitle,TheManIKilled,waschangedtoTheFifthCommandmenttoavoidgiving"wrongimpressionsinthemindsofthepublicaboutthecharacterofthestory."ItultimatelywasreleasedasBrokenLullaby.